The Cave of a Thousand Columns

"BEWARE when the mountain shakes!" was the warning old chief Bal-yari gave Major Rogers as he handed this daring explorer a mystic token of his tribe, sealed in a wooden casket. Engraven on the token were aboriginal signs and symbols explaining the mysteries of vast underground caverns, where lurked wild, weird and wonderful denizens of an unknown world.

So Major Rogers and his two young companions, Ned and Jim, started to explore the marvellous caverns and lakes underneath the mighty mountain, and in their search they discovered "The Cave of a Thousand Columns"—and this is the title of the thrilling adventure story which will be published in serial form in the Young People's Page, of The Age, commencing on Tuesday.

It is a vivid, enthralling story, packed with amazing adventures, which has been written by Mr. T. E. Grattan-Smith, an adventure-loving Australian author, who is splendidly equipped to tell vividly and entertainingly an adventure story of mystery and romance for the thousands of boys and girls who read the Young People's section of The Age. Instalments of "The Cave of a Thousand Columns" will appear in The Age on Tuesdays, Fridays and Saturdays. Remember, "The Cave of a Thousand Columns" commences in "The Age" next Tuesday.

CHAPTER I. THE CAVE IN THE CRATER
CHAPTER II. A DAY OF TOIL
CHAPTER III. A MESSAGE TO MEL
CHAPTER IV. ROGERS EXPLORES THE CAVERN
CHAPTER V. A GRAVE DECISION
CHAPTER VI. MEL RECEIVES BAD NEWS
CHAPTER VII. RIGHT TO THE END
CHAPTER VIII. FACING THE UNKNOWN
CHAPTER IX. THE CAVE OF A THOUSAND COLUMNS
CHAPTER X. THE TOKEN
CHAPTER XI. THE RUSTLE OF WINGS
CHAPTER XII. ON GUARD
CHAPTER XIII. WATERS OF DEATH
CHAPTER XIV. THE DEVIL'S MAW
CHAPTER XV. CANNIBALS OF THE CAVERNS
CHAPTER XVI. A FIGHT FOR LIFE
CHAPTER XVII. THE DEATH PIT
CHAPTER XVIII. A MYSTERY SOLVED
CHAPTER XIX. JUDITH BLAIRCOURT's STORY
CHAPTER XX. THE BLACKFACES GIVE BATTLE
CHAPTER XXI. TWO FIGHTS TO A FINISH
CHAPTER XXII. THE SPIRIT OF THE CAVERNS
CHAPTER XXIII. THE HAUNT OF THE SERPENT
CHAPTER XXIV. LOOKING BACKWARD AND THE CAVE OF PEARLS
CHAPTER XXV. MER
CHAPTER XXVI. PURSUIT
CHAPTER XXVII. BAULKED
CHAPTER XXVIII. LEAD, KINDLY LIGHT
CHAPTER XXIX. GOOD NEWS
CHAPTER XXX. MEL VISITS "BLAIRCOURT"
CHAPTER XXXI. SMOKE SIGNALS
CHAPTER XXXII. HOME

LIST OF ILLUSTRATIONS

The first book edition of "The Cave of a Thousand Columns" contains five half-tone plates by the English artist Ernest Boye Uden (1911-1986). These are not in the Australian public domain and cannot be included in the present edition of the book. The captions under the illustrations are:

CHAPTER I. — THE CAVE IN THE CRATER

FEW men had a more varied and adventurous career than that of Major Rogers, known only to his most intimate friends as Jack. As a Secret Service Officer he had traversed Australia from end to end, and during his many journeys into the vast back country had made the acquaintance of the blacks and had learnt many of their secrets. Rogers was one of the few white men who had ever been permitted to witness their secret ceremonies.

Whilst amongst them, he had made a friend of old Bal-yari, an aborigine of great age who was respected and venerated by the tribes, and who, when his time had come to go to the happy hunting grounds, sent for Rogers and entrusted him with a small package which Bal-yari solemnly assured him would guide him through strange places. He also described an old volcanic crater, in the wall of which would be found a cave, and added warningly:

Old Bal-yari's description of the locality in which the crater was situated convinced Rogers that the cave was identical with one he had already discovered, and which had been used in bygone days as a retreat by bush-rangers. Rogers had come to the conclusion that this cave was the beginning of a system which extended far under the mountains, and had determined, when he could find leisure, to make a thorough investigation. Old Bal- yari's story strengthened his opinion and sealed his determination. Rogers could not undertake the work of exploration unaided, therefore he enlisted the services of three young friends of his, Ned Grattan, son of an old comrade, and Ned's pal, Jim Stanley. Both lads were in their late teens. The third assistant to the enterprise was Ned's seventeen-year-old sister, Mel.

To Mel was assigned the duties of wireless operator and under Rogers' tuition she had become proficient in the use of the Morse code. The expedition was equipped with a complete transmitting and receiving set, and the results of their explorations were to be sent through to Mel. Subsequent events proved the wisdom of this arrangement. Rogers, with the experience gained as chief of the Secret Service, never left anything to chance.

The great day had at last arrived when Major Rogers, true to his promise, led the way to the mysterious cave. Extensive preparations for the adventure had been made, and Ned, Jim and Mel had been greatly mystified by the varied assortment of paraphernalia collected by Rogers for use during their explorations.

"I say, Ned," said Jim, as he looked over Rogers' list, "what the deuce do we want a collapsible boat for?"

"Ask me," retorted Ned; "our old chief has me beaten. He is over in Sydney now buying a small dynamo and accumulators. The Chief has more at the back of his head than we imagine. What does he want with magnesium, gelignite, and a bundle of rockets? Look at the list. A complete wireless sending and receiving set, coils of rope, lines, hooks, chemicals, with sufficient provisions to last months if required. He seems to be fitting out a regular scientific exploring expedition, and when I ask the old oyster what it is all about he only grins and says:

"'All right, Ned, just wait a bit,' then off he goes to confab with Mel about her wireless set. Mel has been appointed receiver for the Chief's new station, situated any old place, broadcasting at any old time, on any old subject. Mel wants to go with us, and it is deuced hard luck on the kid to have to leave her behind, but the Chief did not hesitate a moment when she pleaded to be allowed to join us. 'No, Mel, I cannot allow you to take any risks,' he said. 'Ned and Jim are better able to look after themselves in the places we are likely to visit, but you will be a real help to us if you stay and keep those pink ears of yours open for any wireless signals we may send.' The Chief pinched Mel's ear, and that was the end of it.

"So, Jim, old boy, we must wait until we get to the cave in the crater before getting any further information, but there is one thing we can be certain about; that is, the Chief never does anything without a good reason."

After a speedy journey by car to the foot of the great mountains, the party of adventurers embarked upon the broad bosom of a placid river, which had its source in their giant fastnesses, and which flowed serenely in their shadows.

A motor truck had brought along the gear which was stowed in a roomy launch, wherein it was intended to transport the party as far as the navigable water would permit. Afterwards the journey would have to be continued by rowing boat, and later afoot through the mountain gorges until they reached the crater.

Night found Rogers, Ned and Jim camped at the edge of the crater. At their feet was a blue lake which filled its gigantic maw. A great cliff, which rose sheer from the water's edge for hundreds of feet, made a rugged outline as its crest loomed against the last rays of the setting sun, now sinking slowly in the western sky. From their camping place could be seen the dark outline of the cave's mouth high up in the face of the cliff. It had an eerie look in the half-light, and conjured up visions of olden days when bush-rangers used it as a storehouse for their ill-gotten gains and also as a hiding-place when evading the consequences of their evil deeds.

Rogers gazed thoughtfully at the dark smudge on the cliff face. Who can say what were his thoughts at that moment? But if it had been permitted for others to share his secret, they would perhaps have been transported back through the centuries when in the dark mouth of the cave stood people of another race, perhaps of another shape, when the lake itself was the home of weird and ferocious monsters, who waited for the sacrifice hurtling down from the dark cave mouth into their ravenous and terrible jaws. Rogers awoke from his reverie with a slight start.

"I am sorry, boys," he said, "that I do not appear to be good company for you to-night, but the sight of the cave has always had a strange effect upon me, ever since . . ." Here Rogers stopped, then continued: "Oh, well, boys, perhaps I had better tell you before we begin our work to-morrow, something about what we may expect to find when we penetrate the crater wall at the back of the cave. There is abundant evidence that centuries ago a passage existed which communicated with vast underground caverns. I have carefully examined all the fissures leading from the cave, and among them I found one which bears evidence of having been extensively used. Portions of the rock floor, not covered with debris, showed unmistakably that many feet had passed over it, being worn, and where the harder rock cropped through, highly polished. Our job to-morrow, when we have finished transporting our gear to the cave, is to get to work and remove the obstruction in the fissure. It promises to be a heavy task, but I have made provision for lightening our labours by bringing along that gelignite and other explosives you were so much concerned about. I cannot tell you any more, boys, at present, for I am under an obligation not to reveal what the last surviving descendant of Australia's most ancient line of aborigine kings entrusted to me, until the mountain speaks. What old Bal-yari meant by this I do not know, but I am not violating that trust by attempting to open up the passage, for I discovered it long before old Bal-yari pledged me to secrecy, when he placed in my hand the token which he said would guide me to some great unknown place. I have not consulted the token, yet I believe the cave which you see in that cliff wall is connected with it in some manner. If it is as I imagine, we are on the verge of some wonderful and perhaps dangerous adventures."

The two boys listened with eager attention to Rogers, and when he had finished they instinctively looked towards one another. Then their long-held breath was expelled with a prolonged "Whew!"

"Sounds exciting," was Ned's first remark. "It looks as if this old volcano has some history behind it. What do you think, Jim?"

Jim, thus appealed to, said gravely: "Look here, Ned, to-night I am going to sleep as close to the fire as I can get. That hole in the wall up there gives me the creeps. It looks as if it is ready to spit out confounded dragons or something, every moment you look at it."

Rogers laughed. "Nothing to hurt you up there, Jim; at least not in the cave, but it is what you will find at the back of it that keeps me guessing. Anyhow, it is ten o'clock and time to turn in. We must be up early in the morning and get our gear hoisted."

"Righto, Chief," said the boys together, and Ned, who happened to be looking at the cliff face, suddenly started. "Look, look at the cave! What is that?"

A faint, luminous light appeared within its mouth. Rogers looked at the boys, but did not speak. Yet under his breath he muttered "Um."

CHAPTER II. — A DAY OF TOIL

THE occupants of the camp awoke to the sound of demoniac laughter. Dawn was just breaking, and overhead a pair of kookaburras welcomed the coming day by holding a laughing competition. It must have resulted in a tie, for, when at length they finished their outburst of hilarity, they flew off to another tree and started all over again.

A plunge in the lake while the billy boiled gave the boys and Rogers an appetite for breakfast. Rogers performed the duties of cook in an admirable manner, and his grills straight off the glowing coals were something to remember. However, no time was lost in beginning the day's work. Rogers made his way towards the narrow track which twisted ribbon-like along the face of the cliff. He had provided himself with a light axe and carried a coil of stout rope, also a lighter line to be used for lashings. His intention was to cut saplings for sheer-legs and erect a hoist jutting out over the edge of the cliff at the cave's mouth. This was for the purpose of hauling up the gear and the provisions. It was not possible, owing to the narrowness of the ledge which led to the cave, to carry anything bulky while traversing its treacherous surface.

Rogers cut the saplings and instructed the boys to float them across the lake to a point directly underneath the cave's mouth. He, himself, would reach the cave by way of the ledge, then, by means of the rope, haul the saplings up the face of the cliff. The rest would then be easy, for with the aid of the improvised hoist, fitted with block and tackle, the gear, including the boat, could be hoisted up to the cave without much difficulty. Rogers was soon to be seen traversing the ledge. He looked at that great height like a fly clinging to a wall. Ned and Jim watched him carefully, for later they must both make the same dangerous journey.

Rogers at length reached his objective and, after a few minutes, lowered his rope down the face of the cliff. Ned and Jim were waiting beneath. They had swum across the lake, pushing the saplings before them. Soon the poles were being hauled up to the cliff face and Rogers was presently busy rigging up his hoist. Meanwhile, the boys were engaged stowing the gear away in the boat for transportation across the lake. The boat was of special design; the framework, being built in sections, was easily fitted together, and the outer shell of specially prepared canvas was meant to withstand rough usage. The boat was extremely light, yet serviceable, and built upon generous lines. It had plenty of room for the gear, and ample space left for the comfort of the three adventurers.

For transport over rough places, light wheels were provided. They were about the size of those used on a bicycle, and could be attached at each end of the boat. The boat also had a light guard on either side extending from bow to stern, which prevented any possible damage which might be done to the fabric when negotiating rock-strewn waters. Rogers had also included a small out-board motor to be used in an emergency, as it would not be possible to carry fuel for its continuous use; paddles were provided for the propulsion of the boat under normal conditions.

The work of hoisting the gear now began. The rope was lowered and the first bundle securely attached, and Rogers' strong arms, aided by the double blocks, soon landed it on the floor of the cave. The rest followed quickly, yet it was well into the forenoon before the last load was placed in the sling. Only the boat remained to be hoisted. It had been arranged by Rogers that it remain intact. He would lift it bodily from the water, then Ned and Jim could swim ashore and reach the cave by means of the ledge. Placing the slings in position, the boys slipped overboard and watched the boat leave the water and soar skyward. They remained treading water until they saw that Rogers had hauled it into the cave safely. Then, as they were about to make for the shore, they heard a hail from Rogers, and saw the sling coming down again.

"Good enough, it will save us from creeping along that confounded ledge. Who goes first?" said Jim.

"Toss, you ass! What could we toss with? I suppose you carry a supply of pennies in your bathing trunks."

Ned grinned. "Oh, smoke! I forgot. Anyhow, I'll go first, Jim. There is no risk unless you manage to get your mutton-head underneath and the rope happens to break."

Jim's reply was to put his hands on Ned's shoulders and send him down to the bottom. Quickly slipping into the sling, he signalled to Rogers to haul away. When Ned came up, he found Jim dangling in mid-air with a grin of derision on his face, and his fingers extended in a most uncomplimentary manner towards Ned, who spluttered wrathfully.

"All right, you blighter; just you wait!" To himself he said: "Well I'll be blowed. Jim put one over on me that time."

Both Ned and Jim were typical Australian boys, ever ready for a joke at their own or someone else's expense.

As he went up he could hardly believe that at last his greatest wish was to be gratified, for now he was about to step into the cave itself. The Cave of Mystery.

As Ned stepped out of the sling to the floor of the cave, Rogers said heartily: "Well, boys, we are getting along famously. It was a tough job pulling that stuff up the cliff-face. We will have lunch first, then we will make an inspection of the crevice; after which this old mountain will imagine that there is something amiss with its innards, for I am going to give it a dose or two of gelignite."

Jim grinned. "Going to perform an operation on its appendix, Chief? I bet it will be the toughest surgical operation you have ever tackled."

Ned, who had not forgotten the incident of the morning when Jim pushed him to the bottom of the lake, said with twinkling eyes: "I know of a tougher operation than that, Jim."

"Well," said Rogers with a laugh, "I know of something tougher still, and that is the job of keeping you two young scamps in order. Now, what about having something to eat?"

A supply of firewood had been sent up on the sling, sufficient for their needs during the day, and also for a cosy fire in the night. In a corner of the cave was a rough fireplace, whose blackened stones bore evidence of many a roaring camp-fire. In the roof above, a crevice formed a natural chimney, by way of which the smoke escaped. The cave itself was of great size and the light from the fire, which now blazed merrily, only dimly lit its dark recesses.

While having lunch Rogers outlined the work for the afternoon. The boat had to be taken apart and the gear checked, for even then it was not too late if any important omission had been made, to rectify the error. From long association with the Secret Service, Rogers was very thorough in his methods, and never left anything to chance if it could possibly be avoided. At the last minute, when on their way from the City, he had called at military headquarters and obtained three of the latest gas-masks, also a supply of oxygen. The addition of these articles to the list added greatly to the mystification of Ned and Jim. Then the inspection and clearing of the crevice would occupy the rest of the afternoon. After an hour's work, Rogers gave an exclamation of satisfaction. Everything was in order.

"Now, Ned," he said, "get that battery, flex and bulb ready. We must have some light down there," pointing in the direction of the crevice.

Thirty feet from the mouth of the cave the rock floor commenced to slope downward; another thirty feet and a huge crack in the cliff wall, extending from the floor of the cave to the roof, became visible. Loose stones and sand covered the bottom, through which, in places, the well-worn rock could be seen. The crevice extended back for another twenty feet and then abruptly ended. A mass of stones and boulders filled it completely. Rogers turned to the boys.

"It is our job to shift that stuff. Loop your flex over that ledge, Ned, and put those explosives on the ledge also, Jim, then we will have a good look at it."

Rogers, after carefully studying the surroundings, took his crow-bar and levered out some of the smaller rocks. He continued until he had made a considerable cavity in the obstruction.

"What do you think of it now, Chief?" Ned asked, as Rogers, wiping his hands, sat down on a handy boulder and surveyed his work.

"Luckily, it is just what I thought it was. This passage has been sealed by human hands, perhaps centuries ago. If it had been blocked by a rock fall, we would have had a week's work before we could have cleared it, and nearly every stone would have had to be taken back to the cave and dumped in the lake. That heap of stuff blocking the crevice is, however, not more than six or eight feet through. On the other side of it there is no doubt that the crevice opens out into another cave. After that, well, who can tell? Hand me a plug of gelignite, Jim, some fuse and a detonator. I am going to give it a trial shot—half a plug first, then perhaps something stronger."

Rogers was soon busy fixing the detonator on the fuse, then he inserted it in the putty-like explosive.

"Now, out you get, boys. There may be some loose stones shooting up this crevice in a minute."

Rogers lit the fuse and then retreated to the cave. Keeping out of the line of fire, they waited. Presently a loud explosion was heard and simultaneously, with a vicious whiz, a rock shot through the cave.

"That's the stuff you have to look out for, boys, when you let off shots. That stone would have cut a man in half if it had hit him squarely."

An inspection of the crevice showed that Rogers' surmise regarding the quantity of stone to be removed was likely to be correct. The shot had loosened a considerable amount of the obstruction.

"We will put in a full plug this time," Rogers observed, "then increase the dose if necessary. I do not want to bring the whole roof down on us."

Well on into the afternoon the work went on. The explosions shook the wall of the crater, and if its old spirit could have remembered, it would have been reminded of days and nights when mightier explosions made the earth tremble, for, from that old crater, belched flame and smoke, and molten lava poured from its fiery lips. But that was in the beginning of things. Now it lay cold and stark, its fires quenched for all time, and man, ever seeking fresh victories, was now pounding with Vulcan strokes against the door which had guarded its secret for centuries.

Rogers was well satisfied with the progress they had made, and it now only remained for a final sledge-hammer blow at the obstructing rocks to force a passage. To this end he had placed charges in various places and they now awaited the explosion. Presently came a violent rush of air from the crevice followed by the noise of the explosion, then the rattle of stones as they crashed against the roof and sides of the crevice or shot straight out through the cave's mouth.

After waiting until the fumes had cleared away, they entered the crevice. Where once was a wall of loose rock, they saw a black yawning opening.

"The wall has been blown clean out," said Ned, "and the stuff has mostly gone downwards."

Rogers had provided himself with a spotlight. Stepping into the opening with the boys close behind him he flashed his light below and ahead. The obstruction had in truth been blown out and the explorers could see that they had reopened an old entrance to such a vast cavern that the rays from the powerful spotlight could not penetrate to its farthest end. The floor sloped abruptly from the opening and the roof ran parallel with it. Underfoot were strewn the rocks thrown out by the explosion, but otherwise there was a singular absence of loose rock.

"I think that is running water," he said, "there must be an underground stream down below there somewhere. Switch off that light for a moment, Jim, I wish to make an experiment."

There was a flash as Rogers ignited a rocket, its sinuous length shooting through the cavern unimpeded until, bursting, it scattered a myriad of golden stars. The cavern was lit up as if by daylight, yet to the watchful observers the limits of the vast underground cave could not be determined.

"Our job is finished for to-day," said Rogers. "Let us go back to the cave, have tea, a good night's sleep and then to-morrow— well, who knows what to-morrow may bring forth?"

How true were those words, who was to know? Yet that night it was a merry party that sat round the fire in the cave. Many were the stories told by Rogers of his wanderings, stories interspersed by selections from Sydney's broadcasting stations. The wild denizens of the surrounding bush must have been amazed at hearing the strains of jazz, operatic selections, song and band music, which echoed through the lonely crater. Once a loud "Coo-ee" came through the speaker.

"That's 2FC broadcasting to London," observed Ned, as the aborigine call came through.

"I am going to do some broadcasting myself in a minute or two," said Rogers, "for Mel is just about getting ready to listen in."

CHAPTER III. — A MESSAGE TO MEL

MEL, Ned's sister, was greatly interested in the expedition arranged by Rogers to explore the caves. Rogers had planned the part Mel was to play in the general scheme and had allotted to her the task of attending to the wireless. He had arranged an elaborate private code by which messages could be sent to Mel without becoming known to other receiving stations. Rogers planned to send messages through at a certain time each night, and if an emergency arose in which it became imperative to get into touch with her at other than the stated time, he had affixed a device which would operate upon receiving a certain number of dots and dashes, and cause an alarm bell to ring continuously until Mel had received warning.

Mel sat in her own cosy den waiting for the first message from Rogers to come through. Presently the instrument clicked and the call sign was tapped out in Morse. Then came, "Good evening, Mel." "Cave station No. I in old crater, Blue Mountains, speaking; situation sixty feet up the face of the cliff, surroundings snug, big fire burning, Ned and Jim engaged in a friendly argument—the young scamps are both snug in bunk, Stop. Jim, who read my last remark, wants me to tell you that my yarn about him being snug in bunk was all rubbish—how could he be when Ned had commandeered his best blanket!

"Now carry on, Mel; we have made a splendid beginning—all gear is safely stowed in the cave and an important discovery has been made. We cleared out the blocked crevice with shots this afternoon, and discovered that the cave is connected with another of enormous size—I believe it to be one of a great chain. We have not yet explored it, but will do so to-morrow. We heard the sound of running water, so probably our boat will come in handy later. I was pleased to notice when we broke through that the air was fresh, which indicates openings elsewhere. Last night we observed a curious light which seemed to come from the mouth of the cave. Its appearance gave Jim the creeps, but I have a theory which, if correct, will explain the phenomenon. However, Mel, later I hope to be able to tell you more about it. I have now given you the main incidents connected with our first day's work. Ned and Jim send their love. Ned has just called out 'Tell them at home, Chief, that we are having the time of our young lives.' Love from self, Mel. Good night."

After the last words came through, Mel, full of excitement, rushed off to find her mother and father.

Mr. and Mrs. Grattan were chatting when Mel, her eyes bright with excitement, burst in upon them.

"Isn't it splendid?" was Mel's comment when she had finished reading. "I do wish I was there," she breathed. "The mean things, they might have taken me."

"Don't worry, Mel," said Mrs. Grattan, patting her hand. "If Mr. Rogers had thought it wise to have taken you he would have done so. Now what he has done will probably be all for the best."

When Mrs. Grattan uttered these words, she little thought that within a few short hours her words would be justified, and that Rogers' refusal to allow Mel to accompany them would indeed be all for the best.

CHAPTER IV. — ROGERS EXPLORES THE CAVERN

AT the first coming of the dawn the occupants of the cave were astir. They had slept well after the heavy work of the previous day. A log still smouldered in the fireplace and lent a homely appearance to the otherwise sombre-looking rock cavern. Rogers dropped a bucket down into the lake and soon a supply of cool mountain water was available for a refreshing splash in a corner of the cave. A steaming mug of coffee each was next disposed of, and Rogers, leaving the boys to prepare breakfast, announced his intention of taking a preliminary survey of the new cavern.

Taking a flashlight torch with him, and picking his way over the loose boulders with which the crevice was bestrewn, he soon reached the newly-opened cavern. At the entrance he put out his torch and stood watching intently for a few moments. The cavern looked dark and forbidding, but when his eyes became accustomed to the change from the stronger light of the cave he noted that it was possible to see without straining the eyes. The same nebulous light which Ned had seen emanating from the cave the previous night permeated the cavern, and its presence made it possible for Rogers to distinguish objects near at hand without the aid of his torch.

Rogers proceeded cautiously and at each step became more amazed at the great size of this underground cavity. He had taken the precaution to attach the end of a ball of twine to a stone at the entrance in order that he might find his way out without difficulty. He was not taking any chances of getting lost in what might prove to be an underground labyrinth. For some distance the floor sloped, then, when about a hundred feet had been traversed, it became practically level. Again the cavern narrowed until Rogers thought that he was approaching its extreme limits; but just as he came to the conclusion that his theory of a vast underground system of caves was at fault, the cavern widened out again and Rogers again heard distinctly the trickle of running water.

He had now reached the end of his ball of twine, so placing his torch upon a rock with its rays shining in the direction in which he was traversing, he continued his exploration. He now found himself in a cavern which for size eclipsed the other through which he had passed. Underfoot the way was smooth. Turning occasionally to keep his eye upon the light from the torch, he strode forward with more confidence. His optimism nearly caused his undoing, for, almost without warning, he found himself upon the edge of an abyss from where the noise of running water emanated. His vision could not penetrate to its depths, but it looked evil and forbidding. Carefully skirting its edge and making sure of every step, he followed its course. It led him towards what appeared to be a solid wall, but he found that just before reaching it the contour of the abyss changed. It made almost a right-angle turn, then continued its course parallel with the rock, leaving between it and the wall a path a yard wide.

Rogers' torch was just visible in the distance and he was about to make up his mind to return, when the wall ended suddenly and the course of the abyss turned sharply to the left. Pressing closely against the rock, Rogers turned the corner, and straight ahead through an opening in the wall, found himself gazing upon an underground lake.

Satisfied with his discovery, Rogers retraced his steps, making a mental note of the position of the abyss. Recovering his torch, he rapidly made his way back to the boys, leaving the string for use as a guide when next entering the cavern.

"Well, Chief," said Ned, as Rogers re-entered the cave, "we were just about to make up a search party. Make any discoveries?"

"I did," answered Rogers. "And I nearly fell down a hole in the earth as well. It looked dark and deep enough to be the entrance to the lower regions. It is a chasm cut apparently through the softer rock by the action of running water during untold ages. We shall put our spotlight down there during our investigations. How about breakfast?"

"Ready, sir," said Ned promptly. "Now then, you offsider (this to Jim), shake a leg there! Do your job and serve breakfast for two gentlemen."

"Two?" said Jim with feigned innocence. "Did the Chief bring a visitor back with him?"

Rogers laughed. "Jim scores this time, Ned. You will have to get your thinking cap on if you want to get even. Anyhow, what have you for breakfast, Jim?"

"Fish," said Jim with a grin, as he took a glance at the lake sixty feet below. "They have been rising well this morning. I found half a dozen chirping locusts making an inspection of the cave and lo! with the aid of a hook, line, and the lake below, I turned them into six half-pound perches and Edward the Silent cooked them."

CHAPTER V. — A GRAVE DECISION

DURING breakfast, Rogers gave the boys a detailed account of his doings in the cavern and drew a rough sketch showing the position of the abyss and the entrance to the underground lake which he had discovered.

"It is part of my plan to make a survey of these caverns," he said. "Their discovery is of scientific interest—particularly the presence of light in a place which, under normal conditions, should be shrouded in utter darkness. My theory is that the rocks contain uranium or other ore in which radium is found, and that this rare element occurs in sufficient quantity to be visible in the form of light rays. I can account for the nebulous light in the cavern in no other manner, unless it is caused by the decay of vegetable matter, which throws out a phosphorescent light in marshy places.

"This light is the famous will-o'-the-wisp. However, I cannot entertain that theory, for there is an absence of vegetable matter in the caves. They are exceedingly dry—even the roofs being quite free from stalactites. Therefore, I cannot ascribe the phenomenon to that cause. Later, I shall test samples of rocks taken from various parts of the caverns.

"These mysterious lights have been observed in various localities in Australia and it is assumed that the presence of radium-bearing ore (pitch-blende or uranium) may account for them. However, boys, our job is to explore these caverns, so we may as well make a start at once. We will take the sections of the boat through to the entrance, put them together and then explore the lake. If we happen to come to a dead-end by reaching the limits of the caverns during the morning, I propose making the first cave our headquarters, but if we find that the system is an extensive one, then we can transfer all our gear to the entrance of the lake, and make that our jumping-off place for future expeditions.

"Now, first of all, we must fix a lamp at the mouth of the cavern, and leave it switched on while we are away. It will serve as a beacon-light to guide us back again. We will take with us eatables sufficient for lunch; we need not trouble about taking water, as there is plenty down there."

In a few minutes all was ready, and the task of taking the sections of the boat through to the lake commenced. They proceeded rapidly until they came to the end of the twine left by Rogers, then they advanced more cautiously until they came to the abyss into which Rogers had nearly fallen.

Rogers made an inspection of the cavity by means of the spotlight. Lying full length on the floor of the cavern, he peered over the edge. The spotlight revealed the two perpendicular walls of the abyss, at whose bottom water could be discerned. Rogers judged the water to be on a level with the lake outside, now about fifty feet below.

"Glad I did not tumble down there," Rogers remarked casually. "I would have had some trouble in getting out again."

Skirting the huge rock crevice, they soon arrived at the right angle turn, where the abyss skirted the cave wall, and a few moments after, taking the abrupt turn to the left, they came in sight of the lake.

Once through the passage which separated the two caves, they found a natural dam, on one side of which water was flowing through a spillway which led into the abyss. Its musical tinkle could be heard as it clashed to the rock bottom below.

"My word," said Rogers as they stood looking at the dam. "What a devil's whirlpool there would be down here if this lake should rise suddenly! These caves would be a good place to be out of."

To the left of the dam, extending to the edge of the lake, was a flat rock floor. Not a pebble was to be seen on it.

"It looks as if the water washes over here at times," said Ned, "or else there would be loose stones lying about. It will make a good place on which we can fit our boat together."

"This is the spot I had picked as our starting-point," said Rogers, "so get a move on, boys, and we will get the boat afloat. I think that we had better leave a light here also," he added. "Safety first must be our motto when delving into the unknown."

Putting the boat together was the work of a few minutes, and soon the frail craft, which later was to carry them through many dangers, was floating on the still waters of the lake.

Ned looked at Rogers. "Well, Chief, Captain Cook sailed into unknown seas in a gallant little ship, the Endeavour. Why not call her the Endeavour?"

Ned's suggestion was hailed with acclamation by Rogers and Jim, so the Endeavour with her crew of three set off. After paddling for a few moments, Jim had an inspiration.

'Twas Rogers' turn. "This may be the first of many lakes, so we will call it 'Alpha.'"

So, skimming the water of Lake Alpha, the Endeavour continued on her first voyage.

Astern, the beacon-light could be seen shining brightly, whilst the dim light revealed the dark outlines of the cave walls. They were seemingly afloat on a placid river. No perceptible current could be detected as they paddled onward.

"My word!" said Ned, after they had paddled for a quarter of an hour. "There does not seem to be an end to this cavern. We have travelled a full half-mile and there is the light straight behind us still."

Ned had hardly ceased speaking when Jim announced: "You said your piece too soon, Ned, for here is the end."

It seemed as if Jim's statement was correct, for ahead a dark wall loomed up through the faint light.

It looked extremely solid, yet, when the boat got closer a dark patch opened up, and narrowing to a few feet the lake lay between two walls. Before entering, Rogers directed the boys to cease paddling. Throwing a line overboard with a heavy sinker attached, he took soundings and found bottom at six fathoms.

"Plenty of depth here," he remarked. "Now let us continue on through the opening."

A few strokes of the paddles and the boat shot through the passage into another and broader sheet of water.

"Lake Beta," said Rogers. "It looks as if before we have finished with these lakes we will use up the whole Greek alphabet in naming them. I am quite satisfied, boys, that we have discovered a great system which stretches under the mountains and perhaps even to the plains beyond."

Satisfied with what they had found, the party returned to the entrance of Alpha Lake, where they lifted the boat out of the water as a precaution against a sudden rise of the lake, and stowed it away snugly on a higher ledge, for the flat rock from which they had embarked was not more than a few inches above the level of the water.

"Well, boys," said Rogers, after they had seen to the safety of the boat, "it seems that we are on the verge of making important discoveries. My theories have so far been confirmed by what we have seen this morning. We must now make an important decision, that is whether we will be content to make the outer cave our headquarters, or remove our gear to this spot and make it our base of operations. Now, boys, what is it to be? Ned, what is your opinion?"

Night found the three explorers snugly camped on the ledge of rock at Lake Alpha. A supply of firewood had been brought down and a cheery blaze sent its rays across the placid water.

CHAPTER VI. — MEL RECEIVES BAD NEWS

ROGERS was busy with his wireless. He was getting ready to send a report of the day's doings to Mel, but the cheery story he had compiled for the ears of Mel was never sent. Instead, the message which Mel received, an hour later, told only of a terrible happening, something which made Mel's young blood freeze, which left her sitting as one stunned before her instrument. Then a reaction came.

"What has happened, Mel?" asked Mrs. Grattan as she enfolded the stricken girl in her motherly arms.

"Oh, Mother, it is hard to tell you." But Mel pulled herself together like the little brick she was, and, though her lips trembled, told the story she had just received from Rogers.

"Not more than two hours ago, after exploring some newly- discovered caverns and lakes, they were in camp in the second cavern beside a lake which they had named Alpha or first. During the afternoon they had transferred their camping effects and provisions to the new camping ground, and after tea Mr. Rogers was just about to transmit a message to me when a low rumble was heard and the rock on which they were camped trembled violently. The water in the lake receded, then rose again. The first dull rumble was followed by others in quick succession. Then without further warning a great rush of air was forced through the passage, the whole mountain seemed to shake and a blinding dust cloud forced them to put on their gas masks.

"After the last great crash everything became quiet again, and they then decided to investigate and try to discover the cause of the disturbance. They passed through the passage leading to the second cavern and had hardly passed through when they found their way blocked. What had been the cavern was now a mass of rock. Then the awful truth was forced upon them."

Mel paused and looked at her parents, who had listened with grave faces. There was no need for Mel to finish her story. They knew that Ned and Jim, together with Rogers, their dear, old, trusty friend, were entombed in the bowels of the mountain. As Mel gazed at the tense faces of her father and mother, she uttered the closing words of Rogers' message:

"Yet things are not so bad as they might have been. Providence willed it that we shift our camp to the lake. Had we not done so, Mel, it would surely have been the end, for the crater side in which the Bush-ranger's Cave was situated has apparently collapsed. We are unharmed; in full health and strength. We do not lack provisions, and I feel confident that there is a way out.

"I have only the old aborigine's word for it, but he told me when he was dying of a secret passage under the mountains. Therefore, Mel, keep a stiff upper lip—the boys are facing the situation like true Australians. They never batted an eyelid when they knew what had happened. Convey this message to your father and mother. Ask your father to get into touch with the authorities, particularly my Department. Advise them to have an inspection made of the landslide. We will wait at our present camp until we get a report—there may be a possibility of rescue from this end—if not, we will go on. Arrange with a broadcasting station to put news through to us—we will keep our instrument tuned in to 442 metres. In the meantime do not worry—I feel that we shall get safely out of our present fix. We send our love to all. Good night, Mel."

Captain Grattan, who had listened intently, when Mel concluded, spoke: "That message," he said, "is from a gallant gentleman. There is hope. If human ingenuity and unconquerable determination can find a means of escape, then I have no fear for them, for I have never known Rogers to fail."

Sydney's newsboys were gathering a harvest of pennies, for papers were selling like wildfire in the streets, edition after edition being eagerly bought by the public, anxious for the latest news of the entombed party. They were headed by sensational headlines:

EXTRAORDINARY HAPPENING
A MOUNTAIN SHIVERS
PARTY OF EXPLORERS ENTOMBED
IN TOUCH WITH WIRELESS
REPORTED DISCOVERY OF VAST
UNDERGROUND CAVERNS AND LAKES

Then the story of the catastrophe was told. Mel had given the reporters the text of Rogers' message, but they still besieged her for further news from the entombed party. However, Mel steadfastly refused to divulge further details, for she had received another message in code from Rogers, in which he said:

"I want you, Mel, to keep to our first arrangement. When I arranged to transmit message in code to you, it was with the view of enabling you to derive some benefit from the story of our explorations. You must therefore make terms with the Press and broadcasting stations before releasing our story. It seems cold- blooded to think of such things at the present moment, but, Mel, there is reason in what I am doing, for we are going to win our way out. The boys back me up in this. Ned has just remarked that Mel will be a bloated capitalist by the time we do get out, and Jim has also put in his spoke. 'Not her,' he said, 'Mel will spend it all in face powder.'"

When Mel received this part of Rogers' message, for a moment she became indignant.

"Face powder, indeed! I never use it, the horrid thing." Then she gave a wan little smile. "Dear old Jim," she breathed. Then with a proud toss of her head, she said to herself: "If Jim and Ned can joke in that awful place, then I, too, can be brave."

There was no need for Mel to make that resolution, for she had the staunchest heart that ever beat in the breast of a woman.

CHAPTER VII. — RIGHT TO THE END

ROGERS sat on a rock before his instrument. He was waiting for the moment agreed upon with Mel, when he would commence to transmit his message. With finger poised over the key, he watched the hand of his watch. Now it was just on the tick of eight—but his finger did not strike the key. Instead he started! What was that? An ominous rumbling was heard. Louder and more insistent it grew, then the rock upon which he was sitting trembled violently and a terrifying crash echoed through the cavern. Ned and Jim, who were sitting beside Rogers, sprang to their feet, as a great blast of air swept through the opening. Rogers was the first to realize their danger as a choking dust began to penetrate to their lungs.

Quickly donning them, they waited until the dust-laden air was clear again and they could breathe freely without them. As Jim removed his mask he said: "I think, Chief, part of the cavern has caved in. If it has, we might find ourselves in a bit of a fix down here."

Rogers nodded gravely. "I hope it is not too bad," he said. "We will go back in a few minutes when that dust settles down a little. It is mighty thick in there still. There is no doubt that something serious has happened."

After waiting a few minutes longer they cautiously proceeded through the opening. Rogers had provided himself with the spotlight. Throwing its rays well ahead, the extent of the catastrophe was soon made apparent. Thirty feet from the entrance a dark mass of rock loomed up. What had been an immense cavern had now dwindled by four-fifths. The rock above had fallen and the way out was completely blocked. Rogers saw immediately that their retreat was hopelessly cut off.

Turning to Ned and Jim, he said calmly: "Boys, we are trapped. The crater wall has caved in. It has probably been on the verge of collapse for a thousand years. Those shots of ours have hastened the downfall by perhaps another thousand. 'Tis strange, boys, that the crumbling old crater should fall in at a moment when for the first time white men attempt to wrest from it its age-old secret."

Despite the terrible significance of the happening, Rogers spoke without a tremor in his voice. With the responsibility of the two boys on his shoulders—with but the word of an old aborigine to buoy his heart with hope of escape, Rogers faced the situation without flinching. A man truly of giant courage.

Rogers went back to the camp, followed by the boys. Neither had shown by word or action what his feelings were when they found themselves cut off from the outside world. That is what Rogers meant when he told Mel that they never batted an eyelid. Rogers' eyes gleamed with pride at the undaunted courage shown by Ned and Jim. Whilst the boys themselves, sinking all thoughts of self, had only unbounded faith and admiration for the man they lovingly hailed as "Chief."

Rogers returned to his transmitting and quietly tapped out his message to Mel. He knew that loving hearts would ache at the Grattan home, yet he was helpless to stay one pang of the pain which his duty called upon him to inflict. Both Ned and Jim were proficient with the Morse code. The dot and dash were to them as the alphabet. They listened intently. Ned's sense of humour was, even there, not proof against a quip at Mel's expense, and Jim, the ever-ready, followed close upon his heels. Rogers indulged in an amused chuckle at Jim's unfounded charge that Mel would spend her patrimony in face powder. Like Mel, he realized that danger had no terrors for these two boys.

Morning dawned in the outside world, clear and beautiful as only an Australian summer dawn can be, but there were three who did not see the sunrise. They awoke to see only the nebulous walls of the cavern and the faint shimmer of the lake. Ned was the first to wake; for a moment he had forgotten the events of the night before. Then remembrance came. Ned communed with himself: "Ned, you mutt, ever since you were a kid you have been crazy for adventure, from capturing pirates to exploring the South Pole, but never in your wildest dreams did you ever imagine that one day you would find yourself doing a Jules Verne act like this. It was all very well for him to write a yarn about a journey to the centre of the earth, but I bet the beggar was never even down a coal-mine, but did his journey in an easy chair with his feet on the mantelpiece, which reminds me, Jim, too, was always a glutton for adventure. He wanted to be a mighty hunter, slaying the king of beasts in his lair and capturing alligators, with elephants and giraffes as a side line."

Ned's musings were interrupted by the sound of a splash in the lake. Looking up quickly, he saw ripples forming an ever-growing ring a few yards from the rock. "Fish for breakfast," said Ned to himself. Quickly putting his rod together, he selected a spinner and made a cast.

"Whiz," his reel ran out as a lively perch struck and was hooked. "We will not starve down here, at any rate," was Ned's thought as he landed a fat fish. In ten minutes Ned had more than enough for their wants. Jim and Rogers were still sleeping soundly. Ned placed the fish by the still sleeping Jim, then slipped back under his blanket again. Presently one of the catch, more active than the others, doubled his tail underneath and tried a somersault. He succeeded and landed fairly on Jim's ear. Jim awoke with a start, just as another of the finny tribe performed the same acrobatic feat. Jim's eyes bulged.

"Hey, Chief! Ned!" he called, as he hopped out of his blankets. "The lake is full of flying-fish."

Under cover of his blanket, Ned grinned at the thought that Edward the Silent, as Jim facetiously had called him the day before, had got a little of his own back.

"Yes, Jim," he answered, with a look at Ned, who had apparently just awakened. "They are rising pretty high, too, this morning."

Then Jim saw Ned's rod and line and knew that Ned's remark, "until next time," had not been an idle threat.

It was, indeed, good fortune that a never-failing supply of edible fish was available. It took a big load off Rogers' mind as he saw their silvery bodies kicking on the rock. They could exist for an indefinite period in the caverns without fear of actual starvation. Another feature which would contribute considerably to their comfort was the presence of driftwood in the caverns. Rogers had noticed this the day before when on their way to the lake. Undoubtedly, things did not look so black as they did the previous evening. Fire, fish and fresh water, augmented by a carefully selected stock of concentrated and canned provisions.

When Rogers whistled, only his most intimate friends knew that a knotty problem had been solved.

Breakfast was a cheerful affair; each had made up his mind that no matter what had to be faced they would not wear their hearts upon their sleeves. Such was the spirit of these three— one a man of tried courage, who had at different times faced death without flinching, and two striplings, untried as yet, but true sons of a sturdy people, who guarded with jealous care their heritage, a young and glorious country which one day might become the stronghold of the British race.

Rogers, as soon as they had finished breakfast, provided by Ned, proceeded to arrange the wireless set for the reception of the expected broadcast report, and it was not long before a welcome voice was heard.

"Hullo. Hullo. Station XIX speaking. This message is for Major Rogers, Ned Grattan and Jim Stanley, broadcasting on special wave-length. I hope you will get good reception. Your message to Miss Mel Grattan was received and last night a survey and rescue party was dispatched to the crater. They have not yet had time to send a report, but you can rest assured that everything that is possible is being done. A detachment of engineers has been detailed, with equipment to tunnel, if practicable, through to you. Major Rogers is requested to make a survey and give as near as possible your present position. This happening has aroused the interest of all Australia, who will listen with breathless interest to all accounts of your doings which you may put over the air. It is now Miss Grattan's wish that, instead of sending your messages in code (private communications excepted), you will transmit through the microphone with which we know you are equipped, at eight p.m. each night. This station sends best wishes for your early release. Miss Mel Grattan will now speak to you."

"Hello, hello," came a girlish voice. "Mel speaking, Ned, Jim and Mr. Rogers. Now you are a nice lot of people to go and get into mischief like you have done." (Mel's heart was nearly breaking, but she had said she would be brave, and so she faced the microphone without a tremor, for they needed the sound of a cheerful voice down in that dark cavern.) "Yes," she continued, "I know what is going to happen; you will have heaps of thrilling adventures and I shall be out of all the fun. No, not out of it altogether, for," she added, "I shall hear all about them each day."

Thus Mel sent her cheery message and there were three who listened with eager ears.

Mr. and Mrs. Grattan were next heard. They also added a cheery note of optimism. The listeners in the cavern forgot the danger of their position as the sombre cavern re-echoed with the voices of those nearest and dearest to them. A "God bless you" from the lips of Mrs. Grattan ended the message from home. Rogers disconnected the set. Turning to the boys, he said, simply:

During the next few hours Rogers was busy examining the rock fall and making estimates. He set both Ned and Jim various tasks in connection with the survey. He knew it was best for the boys to have some occupation. Then when all was completed, he sent his message through to the rescue party. They had not long to wait for a reply, for through the speaker came the voice of the chief officer of the engineering corps.

"We are at the crater and probably a quarter of a mile from your present position," he announced; "what you described as the rock face in which the cave, was situated, has fallen into the lake and the mountain behind has moved bodily. Millions of tons of solid rock have obliterated the cave's entrance. We have checked up your estimate with our own survey, and know approximately your position. The work of tunnelling will be commenced immediately. It will be a tough job, but we will reach you without fail. Your information that you have an ample supply of food has allayed our anxiety."

Next followed messages from Rogers' personal friends in the corps. Many a quip and jest was sent through that did not fail to raise a laugh.

"That is good news," said Rogers. "Those chaps outside can burrow like rabbits—well, it is their job. Now, boys, I do not propose sitting down here to wait for them to tunnel through. I have a better scheme than that. This is where old Bal-yari's information comes in handy. We are going exploring, and will try to find a way out ourselves. Our greatest care must be that we do not get hopelessly lost in these underground caverns. We must take bearings as we proceed, and if we come to a dead end, we can return and trust to luck, aided by the picks, rock-drills and shovels of our friends outside, for our release from this end. What do you say, boys?"

Rogers always made a point of consulting the two lads before making a decision. His knowledge of men had taught him that the burden of responsibility, when equally shared, produced better results. It gave rise to the feeling that they, too, were leaders, not merely followers, and as such would shoulder their burdens with steadfast determination.

Rogers' question was answered by both boys in practically the same words. Inactivity had no place in their make-up.

"We will go with you to the limit, Chief." Then they impulsively held out their hands. "Yes, right to the end, Chief," they said, and then each gave the man they loved and trusted a grip of steel.

CHAPTER VIII. — FACING THE UNKNOWN

NEXT morning, after wirelessing their intention to continue the exploration of the caverns, they packed their kit in the boat and set out into the unknown.

The boat glided silently over the still waters of Lake Alpha. The boys were using their paddles Indian fashion. Paddles were handier than the oars, especially when negotiating narrow waters. Rogers sat in the stern and steered towards the entrance to Lake Beta, which they had discovered on their previous trip. It did not take long to make the entrance of the second lake. Through this they passed, and Lake Beta lay ahead.

This lake proved to be much the same as the first, except for the presence of a group of pointed rocks which rose abruptly from the water. They jutted out from the side well into the lake, and Rogers had to change his course in order to clear them. Rounding the outer edge slowly, they observed a great quantity of driftwood, which had been trapped by the rocks, whose formation represented a huge comb with teeth upwards.

"This would be a nasty place to be caught in flood-time," said Rogers. "I wonder how high the water rises in a fresh. This is an event we must be prepared for. A heavy downpour on the mountains might fill these caverns. We had better examine the rock walls for high-water marks."

Paddling shoreward, they brought the boat to shore on the inside of the driftwood. Rogers landed and climbed to the highest point. Fifteen feet up he found leaves and small limbs of trees wedged among the rocks. This seemed to be the highest point the waters had reached. The boys were intently watching the flashes of Rogers' spotlight, when a rustling sound was heard in the direction of the driftwood. In the dim light, nothing could be seen, yet the sound came perceptibly nearer each moment.

"There is something coming towards the boat over the driftwood," whispered Jim. "Get the Winchester ready, Ned; it is nearest to you."

Ned picked up the rifle, which had been handily placed upon a seat in case of an emergency. Then he gave a warning call to Rogers.

"Turn the spotlight on the driftwood near the stern of the boat, Chief!" he shouted.

Quick as a flash, the beam of light lit up the pile. At the same instant Ned's rifle went to his shoulder, and three deafening reports followed in quick succession. The glare of the spotlight had revealed an alarming situation.

Within a few feet of the stern of the boat the hideous head of an immense serpent was up-reared. It was twisting its sinuous body to strike, when Ned brought the luminous sight of his rifle to a dead level between its baleful eyes. Ned's bullet sped true. For a moment the up-reared head poised, then with a convulsive shudder dropped to the driftwood, where ten feet of scaly monster writhed in its death agonies.

As the report of Ned's rifle echoed through the cavern, the driftwood suddenly became alive with crawling reptiles. Ned's second and third shots were aimed at two equally formidable antagonists who had joined in the attack on the occupants of the boat. Each bullet fortunately found its mark, but there was no time to be lost.

Rogers immediately saw the gravity of the situation. Calling to Jim to get the paddles ready, he quickly climbed down the rocks, only to find the way intercepted by another of the monsters, which had wriggled from the driftwood to the ledge of rock, and now, hissing, interposed its length between Rogers and safety. As the reptile faced Rogers, Jim, from behind, seized the paddle. Leaping out of the boat, he swung it round his shoulder, then his strong young arms brought it with a mighty sweep, whistling as it cut the air, across the back of the monster. It fell instantly with a broken vertebra.

"Well done, Jim!" Rogers commended, as he leaped across the writhing reptile and into the boat. With a push from the paddle, the craft shot out into the lake.

After paddling some distance in order to put a safe distance between themselves and their dangerous enemies, they stopped. Rogers wiped his face with his handkerchief, as he said, "Hot work, boys; you handled that lot well!"

"Ned," said Jim, "I have always wondered where all the snakes come from. Now I know. Anyhow, most of them in that driftwood will be orphans from now on, for that beauty you potted first must have been the daddy of the lot."

"Yes," said Rogers, with a laugh; "and the one you clouted with the paddle, Jim, must have been his better half. We shall have to be very careful where we camp. We have had one lesson— that is to keep clear of piles of driftwood. They are apparently not healthy places to frequent. However, perhaps we may not see another reptile. There may be some outlet about there, but if there is, they can have it all to themselves. There would be a chance for only one man to get out that way, and I do not think that even St. Patrick himself would take a risk on it.

"Those snakes were of exceptional size. A black snake of seven or eight feet in length is the largest usually found. But I would sooner meet one of those fellows in the bush than a tiger-snake or death-adder. These two have larger fangs than most other venomous snakes, and inflict a deeper wound. Their poison is also more deadly."

As Rogers talked, paddling had been resumed, and the boat made good progress. The lake had now narrowed, considerably, and they found themselves negotiating a huge passage with an arched roof overhead. There was a slight current now observable, due no doubt to the waters being confined within narrow limits. The character of the cavern roof and walls began to change, becoming more rugged, while here and there small stalactites could be seen hanging from the roof above.

"It looks as if we are getting into limestone country," said Rogers. "If so, we shall have more difficulty in making progress. However, I am glad to see that there is a current here. We shall require a swiftly moving stream presently for the power required to charge our batteries."

Ned looked around, then said, with a grin at Jim: "The Chief's going to find a water-wheel somewhere down here in a minute or two, Jim."

"Both wrong, boys. If that water-wheel were alive, it would bite you, for you are sitting on it."

"So that is what it is," he said. "I have been wondering what was in that box ever since we started. I wonder," he continued, "do you ever forget anything?"

"Yes, sometimes. I forgot, when we came down here, that there was a chance of the back door slamming, and slam it did."

"Yes, I heard it. So did Jim. Didn't you, Jim?" Jim, thus appealed to, nodded. "Yes," he said with forced gravity. "I heard it all right, and there is only one other slam I ever heard that beats it."

Ned did not deign to reply, but gazed thoughtfully at the box which contained the water-wheel. At length he spoke.

Rogers, caught napping and not suspecting anything ulterior in Ned's remark, asked: "A gas engine, Ned? Where would we get the gas to run it with?"

Ned, without moving a muscle of his face, and looking solemnly at Rogers, said: "Ask Jim, Chief."

With the change in the character of the rock of the cavern, it was found necessary to use the spotlight. They had evidently passed out of the belt which contained radium-bearing ores. The nebulous light which had made progress comparatively easy had given place to absolute darkness, which became fearfully oppressive when, for economy sake, the light was switched off and they had to grope their way with only an occasional flash to take bearings. Luckily, the channel through which they were passing was comparatively free from turns, and no cross streams were met with. This was fortunate, for a deviation from the main system might mean early disaster.

After proceeding for many miles, the channel widened out, and joined another lake. The cavern in which they found themselves was of limestone formation with the water free from obstacles.

"I think there is going to be a change of scenery down here presently," said Rogers. "I have an idea that we are nearing the end of this chain of lakes."

An hour later, Rogers' surmise was proved to be correct, for their way was blocked. Running water could be heard distinctly. The spotlight revealed a rocky shore of huge boulders, which receded into the darkness. The sound came from this direction, while at their feet water could be seen gushing from among the stones.

"We had better camp here for a time, boys, and investigate. I think back there," pointing into the darkness, "are falls of some kind. Perhaps an overflow from another lake. It means, in any case, transporting our gear. We shall have lunch, then explore."

Some dry wood was found and a merry blaze lit a portion of the cavern. Rogers made preparation for lunch, while Ned and Jim, fitting their rods together, tried their luck with the finny inhabitants of the lake.

"Done," said Ned, and soon an angling contest was in full swing. Nothing happened as Ned and Jim made cast after cast.

"Looks as if we are going to draw a blank," said Ned, as he again made a throw. Ned had spoken too soon, for the spinner had barely flicked the water when away went his line with a rush.

"Wake up, you somnambulist," laughed Ned, as Jim failed again and again, while Ned landed his third catch.

Then Jim's turn came. Making a cast, he hooked his victim. Ned's eyes widened to see the way Jim's rod bent when he attempted to stay the rush of the fish. Jim played it in a masterly fashion, and soon, with the aid of the landing net, landed his catch safely on the rocks. Ned stared when he saw the size of the fish which Jim had placed to his credit. Just then Rogers looked up from his task.

"Yes, Chief," replied Jim, with a side glance at Ned. "One fish and three sardines. By the way, Ned, I would toss yours in again if I were you. There might be a fishing inspector down here somewhere, and you might get a summons for catching undersized fish."

Afternoon found them toiling up a steep incline. It was dry underfoot; the water they had seen gushing from the rocks at the lake side was evidently percolating through many feet below. The way was rough, and numerous boulders had to be surmounted before they reached the top of the rise. As they progressed, the roof arched out above them. At the summit they paused. Intense darkness, lit only by the rays of the spotlight, surrounded them.

For some minutes they traversed the rocky patch, then, flashing his spotlight ahead, Rogers gave an exclamation of surprise. They had arrived at the end of the passage. Holding their breath, they gazed at the wonderful sight before them. They were at the entrance of a cave. No pen could adequately describe the beauty of the scene which had burst suddenly upon their vision.

CHAPTER IX. — THE CAVE OF A THOUSAND COLUMNS

"THE Cave of a Thousand Columns," the leader said. Thus, in a phrase of six words, Rogers described this remarkable scene. It was indeed a cave of a thousand columns. From the great roof stalactites had formed during untold ages, until at length, uniting with the stalagmites, they fashioned the wonderful pillars which appeared to be supporting the roof. Between the pillars, smaller groups of stalactites hung from the roof like a fringe of crystal beads whose colouring under the rays of the spotlight varied from amber to a delicate pink, while the pillars (some were formed like the Corinthian pillars of an ancient temple) were of dazzling whiteness. Nature, working slowly but surely in this dark underground cavern, had evolved a masterpiece of beauty.

On the right, a clear stream of water could be seen. It ended abruptly at the edge of the rocks on which they were standing, while the distant roar of falling water indicated the presence of falls of considerable size.

Viewing the manifold beauties before him, Rogers thought of the old aborigine, and the legend that a race of people once inhabited, or had used, these caves as a secret way through the mountains.

As he stood deeply in thought, the rays of the spotlight fell directly on the base of the mighty column.

Ned, whose eyes were concentrated on the objects revealed by the light, suddenly became tense. Something lay at the foot of the great pillar.

Quickly making his way to the spot, he gazed at the object for an instant, then motioned Rogers and Jim to join him.

Against the base of the pillar, in a sitting position, was a skeleton. Was it human? The same thought flashed through the minds of the three.

Rogers bent to examine the remains. After careful examination, he said: "It is not a human skeleton. Excepting for the pointed horny substance about six inches in length which grows upward from the top of the head, it resembles one; the breast bones, ribs and the thigh bones, also are similar to those of a human being, but the feet were webbed. It has arms also, situated under the wings, whose hands had a thumb and index finger, while the third and fourth fingers were webbed."

"This is a remarkable discovery. It indicates the presence of other beings besides ourselves down here. This skeleton is not very ancient. It looks as if the late owner sat down with his back to the column and died there in the darkness. Perhaps there may be living creatures in the cave. It is advisable to make a search."

The boys agreed with Rogers' suggestion, and, setting off in the direction from which the sound of the falls could be heard, they examined the cave floor for further relics, but were not successful in their search. The cave seemed endless as they wound their way between the great pillars; but at last they arrived at the foot of the falls.

From an immense aperture in the solid wall of the cave, about fifteen feet above them, an unbroken stream poured into a crystal pool beneath. The water flowed over a smooth overhanging ledge thirty feet wide, flanked on each side with a stairway of loose stones which led to the top of the fall. Scrambling up, they found themselves at what, viewed from their position at the top of the falls, appeared to be the outlet of an underground river. Further back it widened, and, flowing only inches deep over a smooth rock dam a hundred feet from the outlet, it joined another underground lake. Rogers' eyes gleamed with satisfaction.

"I was afraid when we first saw the limestone cave that we had lost the chain of lakes, but we have evidently crossed a very narrow belt of the limestone formation, sandwiched in between the older radioactive rocks. We shall, I hope, soon get out of this oppressive darkness. We have strenuous work before us to transport our gear to this lake. We will now return to camp. After we have rested and slept we will push ahead."

The journey back to camp was accomplished without misadventure. Tired and hungry, the adventurers made preparations for spending yet another long night in the bowels of the earth. Something might be made of the fact that, in the caverns, night and day had lost their meaning.

CHAPTER X. — THE TOKEN

THAT night they again received news from the outer world, and listened with intense interest to a detailed account of the tunnelling operations which had been commenced for their release.

The announcer's voice rang with cheery optimism, and, when concluding his report, he said:

"There are some boys here in the studio who wish to send greetings to their two chums. Stand by!"

The next moment Ned and Jim were electrified by hearing their college war-cry, given on many a football field where they had led the team on to victory. Both sprang to their feet.

"We will send that back to them, Chief, as soon as you are ready to transmit," they cried.

Rogers looked quizzically at the two excited boys. "That was their last item," he told them.

"We will now change over to the underground cave station," was next heard. "Cave Station, you are now on the air."

Standing a few feet from the microphone, Ned and Jim gave a lusty reply to the effort of their chums. With the grim spectre of death hovering just beyond the feeble light from their camp fire, in their college cry these boys sent their defiance ringing through the caverns so that all might hear, and know that they remained undaunted.

Rogers, unemotional, with nerves of iron and muscles of steel, sitting before his instrument, gave a graphic account of their activities during the past twenty-four hours. He described the finding of the skeleton in the cave and theorized about its origin.

"The discovery will cause much scientific discussion should we be fortunate enough to have this great system of caves opened up," he went on. "The skeleton is unique. I cannot identify it with any previously discovered remains of prehistoric man, bird or beast. One point is worthy of notice. The skull does not recede, as in the case of the lower human types, and I have come to the conclusion that, when in the flesh, the creature would be possessed of fair intelligence."

The trained, keen eye of Rogers had correctly read the story of the skeleton. That his deductions were sound was proved conclusively at a later stage of their journey in the remarkable adventures which befell them.

"Do you remember I told you I had received a token from old Bal-yari? Well, the time has arrived when we must consult it. It may help to guide our future movements."

Settling themselves comfortably by the camp fire, Rogers produced a package eighteen inches long by nine inches wide. Removal of the outer wrapping disclosed a flat box. As fastenings, sinew was tightly wound about it. The box was cut from a solid block of cedar and was not more than three inches deep. In addition to the sinew fastenings, the lid was cemented by some kind of gum or resinous substance. So firmly had it set that Rogers, with difficulty, prised it open without damaging the box.

The removal of the lid disclosed two objects. One was shaped like a boomerang and was also covered with resin. This proved to be so hard that Rogers found it necessary to use his chisel before an impression could be made upon it.

"My word," he commented, as he chipped. "If we could make a cement as tough as this there would be a fortune in it."

Rogers' perseverance resulted in the discovery that yet another layer of wrapping would have to be removed before the jealously-guarded contents were laid bare. However, it proved to be the last. It was composed of strip after strip of soft ti-tree bark, the unwinding of which was watched by Ned and Jim with intense curiosity. As the last piece fell from Rogers' fingers, the boys exclaimed simultaneously: "It is a boomerang, Chief."

"No, boys, it is not a boomerang, although at first sight it looks very much like one."

With the boys peering over his shoulder, Rogers examined the object. They saw a flat piece of ebony-coloured wood, shaped like an L square but closely resembling a boomerang. Upon it were several engravings. On its handle, or longer end, was an accurate carving which they readily identified as representing the sun. The bend of the L was engraved with another carving of the sun.

"The larger carving of the sun, I think, symbolizes its rising, and the smaller its setting," he said presently. "Now, as the sun rises in the east, we will take that as our starting point. We may safely assume that this token presents a rough map of these caverns and lakes. The carving next to the sun is a cone-shaped mound, with its top broken off. A black spot shows near the middle of the cone. Now, what does that suggest?"

"Don't ask me, Chief," Jim protested. "I was never any good at picture puzzles."

Ned, thus appealed to, looked long and earnestly at the carving. Suddenly he visioned the cave in the crater as he saw it the evening they camped at the edge of the lake with the setting sun as a background for the crater's rugged edge.

"I think you are right, Ned," Roger concurred. "Yes, the next marking of two parallel lines must represent the first cave—the cave of the abyss. Next is an oval, intended, no doubt, for Lake Alpha. Two more parallel lines make the tunnel, and the other oval is Lake Beta. But what do those wavy lines like the letter 'm' greatly exaggerated mean?"

Jim sat deep in thought. Those lines fascinated him. They reminded him of something very real yet elusive. Thoughtfully he raised his eyes and his gaze rested on the boat sculls which had been placed on the rocks.

In an instant he was transported back to Lake Beta. He saw the driftwood pile and Rogers' retreat to the boat cut off by a huge serpent. He felt again the shock as he struck with the scull and broke the monster's back.

"Snakes are what those lines mean," he declared. "The chap who carved this thing probably had good cause to make a record of their whereabouts."

The significance of the wavy lines being determined, the next design claimed their attention. It was composed of a group of three perpendicular markings.

"They are cricket stumps," he said. "Some team has been playing a match down here and forgotten to pull them."

"They would take some pulling," Rogers demurred. "Have a good look at them, Ned."

"Come, Ned," Rogers twitted. "You have studied the drawings closely enough, now have a look at the originals." And he pointed to three massive columns which stood like an advance guard apart from the others.

Ned looked in the direction in which Rogers was pointing, and his eyes twinkled.

"Smoke, Chief!" he said seriously. "It's a pity that we do not use stumps that size in our matches."

Ned glanced sideways at Jim, then fired his shot. "If we did," he added, "they would give Jim a chance to capture a wicket occasionally, and improve his bowling average."

Jim snorted. He was the best bowler in the college team, and Ned's suggestion that he was capable only of hitting a wicket the size of a house left him speechless with indignation.

"There you are, Chief," continued Jim's tormenter, "Jim hasn't a word to say, but I bet the beggar is thinking hard if he can contrive to get the rules altered. Sorry I mentioned it; it will break his club if it has to find funds to buy timber big enough for Jim to hit once in a blue moon."

Jim at length found his voice. A grin overspread his face. As a complete answer to Ned, he uttered a single word, "Koongall."

Ned immediately experienced an uneasy feeling that Jim had delivered a knock-out. Although he cudgelled his brains for the answer, he eventually gave up the struggle and awaited the time when Jim should think fit to enlighten him.

The passage of arms was promptly forgotten by both boys when Rogers, placing a finger on the token, said: "Here are the three columns, and the two designs immediately above represent the falls, with Lake Gamma next. Therefore, up to that point, we have verified the correctness of the map outlined on the token. Beyond that, it is a matter of speculation as to what really awaits us. Although the map shows the continuance of the system of rivers, caves and lakes, the position of the sun indicates the furthest point west. As you see, it is carved in the curve of the boomerang, so the system makes a left-angle turn towards the south. It is quite probable that we have a journey of hundreds of miles before us if we decide to reach the end. The larger the system the better chance we will have of eventually finding an outlet. One factor is the possibility of this system linking up with other known systems. It may be that the caves we are now in extend as far as the border of Victoria. Some time ago, when I visited the Jenolan Caves, one of the guides who had done excellent work in the way of opening up new caves, said that the full extent of that system would never be known. He ventured his opinion that a great proportion of New South Wales is honeycombed with great caves and subterranean rivers. When chatting to the guide, I did not anticipate that I would one day prove, at least to myself, the truth of his statement.

"Nature has worked many marvels when fashioning this old world of ours. This limestone cave with its wonderful pillars probably had its beginning under the sea millions of years ago. Then, pushed up from the ocean bed in a solid mass, we find it to-day carved by the action of water and corrosion into most wondrous shapes, and some day, when untold millions of years have passed, it will again have the ever restless waters of the ocean above it. In a comparatively recent geological period, Mount Kosciusko, our highest mountain, had ice two thousand feet thick upon it; yet it has gone, and of old Kosciusko itself, now just over seven thousand feet high, nothing will remain. It will be levelled to the plains.

"Forgive me, boys, for perhaps wearying you with my talk, but old Mother Nature casts a spell over me at times. Her voice is in the stones beneath our feet and through them she tells her innermost secrets to all those who would learn."

Both boys listened with eager attention. Rogers had the oratorical power of making even the most commonplace events interesting. A born leader of men, he never spared himself if he could be of service to others. Even in his talk to the boys he had an object in view. Ever conscious of their perilous position, he sought to distract the attention of the lads from the ever- present menace. Rogers was indeed a guide, philosopher and friend.

While Rogers was speaking he had picked up the second object contained in the cedar box. At first sight it appeared to be a solid block of wood, oblong in shape, in length about three inches and slightly more than one inch deep. The top edges were cemented, which suggested that it had a lid. The top was decorated with a number of the same kind of wavy lines which ornamented the token.

"Another mystery, boys. We might just as well see what is in this, too," he decided.

The chisel was again requisitioned and the cement chipped off. Its removal disclosed the join between the lid and the box. Inserting his chisel, Rogers prised it off.

A gasp of astonishment from the boys greeted its removal. The block of wood was hollowed out two-thirds of its depth. Coiled in the bottom lay a snake with head flattened over the centre of the coil. Encircled by the serpent lay a shining pearl. The evil head of the serpent seemed to be guarding the treasure which lay within its coils. Although fashioned out of clay, its appearance was lifelike and sinister.

"I wonder what is the answer to this riddle, Chief?" Ned broke the silence. "And what does the pearl mean?"

Rogers, meanwhile, was examining the pearl through a pocket lens. It was not possible to remove it from within the coils without breaking the serpent's head off.

"A perfect pearl if ever there was one," he said. "I do not know what significance or what connection it has with these caves. This I know: old Bal-yari must have had some very good reason for its inclusion with the token. It does not seem possible that this pearl was found in these caves, yet it is not impossible. Sea-shells have been found in the mountains overhead- -in fact, they are of common occurrence. Who shall say that this pearl did not originate in some ancient plant mussel? The story told by the token has thus far been proved to be correct. The pearl and the serpent may also have a story to tell. Serpents, we know, frequent these caves, but whether the imitation in this box has reference to those we have already met, or to more formidable antagonists lying in wait ahead, we cannot tell; but forewarned is forearmed. Although I did not anticipate meeting reptiles, when I decided to bring along the rifle, I made provision for its effective use even in the dark."

Rogers, as he spoke, opened his kit and produced a torch hardly different in appearance from the ordinary flashlight torches with which all three were provided.

"This is a Winchester focusing torch for attachment to the rifle. It is for night shooting and is effective up to a range of three hundred feet. It throws a beam of light on the object aimed at, and is so arranged that wherever the beam of light strikes, there also will the bullet strike. It merely means finding the target with the beam and then pulling the trigger. I have used it, and I know that with it the rifle is deadly sure within the range of the beam."

In a few moments Rogers fitted the attachment to the rifle. Then he said: "Now, boys, we will turn in. We have heavy work ahead to-morrow. We must be afloat on Lake Gamma some time during the morning. Now, off to your blankets!"

Jim was soon in his bunk, but Ned's eyes happened to locate a scrap of newspaper wrapping. Picking it up, a heading in bold type caught his attention. Reading on, he found the name "Koongall" staring him in the face. He read on with feverish haste. "Koongall" was what Jim had called him. Ned did not have to read very far before he discovered the meaning of the name. "Koongall" was the champion Queensland racing goat.

"Very well, James," said Ned to himself, and crawled between his blankets to meditate.

CHAPTER XI. — THE RUSTLE OF WINGS

MORNING found them toiling up the rocky side of the falls with their belongings. Camp had been struck at an early hour and the work of transportation commenced. It was laborious work, but they tackled it cheerfully. Load after load was deposited at the top of the falls where the water from Lake Gamma flowed smoothly over the natural dam.

It was nearly noon before they sat down to a well-earned rest. The boat was floating serenely at their feet as they partook of an early lunch, part of which was a contribution from the waters of Lake Gamma. Fish were still plentiful and the casting of a fly or spinner invariably resulted in the capture of a goodly-sized fish.

As they sat discussing their plans for the day, Rogers, who was speaking, stopped abruptly in the middle of a sentence, and listened intently.

"I thought I heard something unusual, a rustling or whirring sound. But perhaps it was only the falling water below us."

Amid silence, broken only by the splashing of water, they listened—for what, they knew not. What deadly menace was there hovering behind the veil of that inky darkness? Something perhaps at that very moment waiting an opportunity to strike, suddenly and relentlessly, at the three helpless and unwilling intruders into that domain of perpetual night.

"Boys!" Rogers broke the silence. "There are living things in these caves besides the snakes, fish and ourselves. I am inclined to think that we will soon solve the mystery regarding that skeleton seated at the foot of the column down in the cave. Hitherto I have not thought it necessary to have a watch kept, but I think it advisable that from now on one must stand watch while the others sleep. We will divide our sleeping hours into watches. They will be lonely hours for whoever happens to be on guard, but it has to be done, for we cannot afford to take any risks, either personally or of losing our boat or stores. These we must guard jealously, for upon them our safety depends. We will also keep our automatics handy in case of emergency, but we must use them only in the greatest extremity. We may find the denizens of these caves harmless, or we may find them evil; but we must not do anything that would make them our enemies. If my theory that the remains we found in the cave of columns are the prototype of our mysterious visitor, we can expect to meet a race of bird-men in these caverns. Yet we may have been mistaken, or our imagination may have been playing tricks with us. But we must not worry about what may happen. We will take that rustle of wings as a warning and be prepared to meet whatever comes with at least a fighting chance of coming out on top."

"Right, Chief," Ned concurred. "Jim and I both heard something unusual, so we will have to discount the suggestion that our imaginations had run riot. Jim's does sometimes," he added with a laugh, "but not in this case. We both heard it, so we may as well be prepared. I suggest that, as an added precaution, we place wire round our camping places. Just a strand so that a touch will give the alarm. There is nothing much more we can do except keep our eyes peeled day and night, although day and night are all the same down here."

"A good suggestion, Ned," Rogers commended. "We have the wire and current, so an alarm can easily be fixed up, and perhaps we could arrange it so that contact with the wire would touch off a small charge of magnesium powder, whose light would probably reveal any undesirable intruder who may be prowling around. Whoever happens to be on watch can keep the spotlight ready to focus on any unusual object which may be revealed. The flare of a charge of magnesium should have a disconcerting effect on any denizen of these caves and blind him momentarily. The spotlight would have practically the same effect. In the spotlight and magnesium powder we have two important allies which we must use to the best advantage if necessity arises. We could also strengthen our defence by exploding a stick of gelignite which would strike terror into whatever or whoever endeavours to molest us. We have an advantage over the occupants of these caves, if occupants there be, in having at our disposal scientific weapons of a most deadly nature, but we must not use our power needlessly. I have always had a distinct aversion to killing or maiming, and, boys, I know that you are one with me in that respect. If life is in danger, it is perhaps excusable; but wanton killing of bird or beast is, to my mind, a crime and a misuse of the power with which man, as a superior being, has been entrusted."

"Moralising again, Chief," said Jim laughingly. "Why, Ned would not kill a rabbit if he were starving, would you Ned?"

Ned, thus appealed to, and remembering that Jim had called him "Koongall" answered with studied calmness: "You are quite right, Jim, for which you may consider yourself lucky."

The boat, already afloat and loaded, was tied to the rocks which fringed Lake Gamma. It only remained for them to gather up the utensils used in their repast to be ready to embark.

In a few moments all was ready and Rogers gave the word to shove off. Their embarkation on the waters of Lake Gamma seemed to them to mark a vital stage of their journey. Once more through the darkness they paddled their craft, only the light from a torch being used to penetrate the inky blackness ahead. Prodigal use of their batteries was to be avoided, although, up to the present, heavy demands had not been made upon them. Rogers purposed recharging them at the first camping place where running water was to be found. It was just after noon when they left the falls and the cave of columns, yet at six o'clock, they were still moving on. The lake seemed to have no end. Mile after mile they traversed, until the splash, splash of their paddles began to beat hammer-like blows upon their consciousness. The silence otherwise was appalling. For a time after setting off they had chatted one with the other until a paralysis of thought seemed to grip them and they lapsed into silence. It seemed impossible to shake it off. A lethargy of mind and body had seized them. Even Rogers was affected.

The manipulation of the paddles became automatic action. On, on. Would it never end? "If only something would happen to break the spell of this horrible silence," was the thought that persisted in flashing through their tortured brains.

Startlingly their fervent desire was gratified. Again from the darkness came the ominous beating of wings.

CHAPTER XII. — ON GUARD

With paddles poised, Ned and Jim listened. Quick as thought, Rogers flashed the spotlight across the lake. Its rays searched the cavern, but nothing was to be seen. Yet, far up near that rocky roof, something moved. Something watched with intent eyes the boat with its three occupants floating on the water below, something that moved from one rocky projection to another, and, without apparent effort, dropped as light as a feather from a dizzy height to the water below. Without making a ripple it sank beneath the surface, to reappear within touching distance of the boat. A claw-like hand was thrust upward, but it was silently withdrawn. Now a dark body crept out of the water, and, with uncanny spring-like motion, rose into the air to glide silently to some fresh vantage point, ever-watching, ever-waiting.

"We must make camp, boys." Rogers' voice broke the stillness. "That rustling sound will have to be investigated. We have had a long spell on the lake, but we seem to be as far off the end as ever, so the best thing we can do will be to find a camping place somewhere along the shore. Paddle closer in shore, boys, so that I can spot a likely camping ground with the torch light."

Carrying out Rogers' directions, Ned and Jim paddled along the shore line, but there was no landing place to be seen. The walls of the cavern rose sheer out of the water.

They proceeded for some time without better results. Minute after minute passed, but the same forbidding wall kept sliding past.

"Not much chance of a landing here, Chief," said Jim. "Shall we try the other side of the lake?"

"The question is," Rogers objected, "where is the other side? This seems to be a small inland sea. Anyhow, we cannot do any harm in trying, and perhaps we might be able to shake off that mysterious shadower of ours."

Rogers spoke lightly, but none knew better than he that the menace was still very near. As they were about to put Jim's suggestion to the test and look for a landing place on the other side of the lake, the contour of the rock wall changed, and they found themselves rounding a point into a little bay where the rock wall sloped to a flat ledge of rock, which bordered the water's edge.

Weary from a long day's paddling, they were not sorry to find a haven in which to rest. Their experiences during their voyage upon the waters of Lake Gamma had been enough to try the stoutest nerves. The discomfort of the journey had been accentuated by the knowledge that, under cover of the darkness, their every movement was being watched.

Exhausted in mind and body, the prospect of being able to stretch their cramped limbs after the constraint of the long journey in the boat, appealed irresistibly to them. Swinging the boat alongside a ledge of rock, they slipped ashore. The work entailed by the landing of their gear and making camp, came as welcome relief after the deadly monotony of the past hours. As they toiled, immediate danger was forgotten, until, by the time their tasks were completed, their spirits had regained their usual buoyancy.

Hitherto, they had been enabled to sleep without fear of molestation, but, with the discovery that the cavern held other habitants who might prove to be hostile, they decided to take every precaution against surprise. Their prearranged scheme of placing wire round the camp was carried into effect, but they realized that, however effective it might be in giving warning of an attack by way of the rocks, they could not guard against a sudden attack from the air. They must, therefore, rely upon the alertness of the sentry on watch to frustrate any move from that direction. As the boat was their only hope of salvation, they must guard it at all costs. It was, therefore, lifted out of the water and placed against the rock wall behind them, a jutting ledge giving it protection from above.

It was perhaps well that the precaution was taken to place the boat on shore, for the keen eye of Rogers, ever-searching, detected a ripple on the lake which he knew was caused by some body moving swiftly, but silently, through the water. He could trace its movements by the course of the ripples. Something was passing and repassing out there in the shadows, causing a miniature wave to beat along the shore.

"It is back again," Rogers replied, pointing to a ripple on the water, made visible by the light of the fire.

"Whatever it is, it has taken a fancy to our company. Focus the spotlight upon it," Ned urged.

The bright light flashed over the lake, and, at a point directly opposite the camp, for an instant a moving object could be seen, but it sank from view immediately. With its disappearance, the ripples ceased.

"So that's that," said Rogers. "I wonder when it will make its next appearance?"

That event was much nearer than Rogers or the two boys imagined, for the stage was being set for a dramatic introduction to their mysterious watcher—a meeting that was destined to culminate in a series of strange happenings which had no parallel in human experience.

It was inevitable that, during their evening meal, the conversation should centre round the creature which caused them so much uneasiness of mind. They discussed the finding of the skeleton and its possible connection with their furtive pursuer.

"There is no doubt that we are being shadowed by one of a race of Birdmen which inhabit some part of these caves, and whom we probably will have to face sooner or later," said Rogers. "What puzzles me is that there is only one. If it were a scout, we should undoubtedly have had a visit from the rest of the tribe before now. The fact that it makes its appearance at short intervals proves that it does not go very far away. It may have lost its way in the caverns or perhaps may have been outlawed and banished from the main body for some crime committed against their laws. It is quite feasible that this is the solution of the puzzle. Banishment may also have been the fate of the original skeleton. It may be that this one, in its loneliness, has welcomed our appearance, yet does not dare to make closer acquaintance. If this theory is correct, we may have nothing to fear at this stage. I have been thinking about Bal-yari's token. On it we have traced our progress as far as this, the third lake we have traversed. Let us consult the token again."

Rogers produced the carved token and, placing his finger on Lake Gamma, said: "This lake is of immense size, for we have not reached its limits after a day's journey. Now, look at the next markings.

"On the token, two parallel lines are six times the length of the lake we are now traversing. If the map is drawn to a rough scale we are still a great distance from the next lake, which I surmise is the home of our stray Birdman. It is shown by a much larger oval than those denoting the lakes we have passed through. The parallel lines must represent a river of great length connecting this lake with the next. The markings in the centre of the large oval clearly represent one of the Birdmen, and that is the place at which I think we shall find them.

"Now, beyond the lake of the Birdmen, is a chain of three more lakes connected by short rivers; then we come to another large oval with another Birdman design. This must mean that another tribe dwells there. This second oval is situated at the curve of the boomerang which now runs in a southerly direction. At the southern end of the large oval two more parallel lines are shown connecting with a lake; these lines represent rivers connected with yet another lake. The markings in the centre of this design are similar to those just beyond the Cave of a Thousand Columns; therefore, they must represent falls. We have now come near to the most southerly end of the boomerang where the river branches in three directions, but where they lead to, who knows?

"From the knowledge we have already gained, that is my reading of Bal-yari's token or map. What connection the pearl and the serpent have with these caves, we can't even guess at," Rogers concluded.

The night was far advanced before Rogers gave the signal to turn in. The nightly transmission of their doings had been sent by Rogers, and the three had listened to the news from outside. This night they must stand guard in turn over the camp. The first watch fell to Jim, the second to Ned, and Rogers drew the third.

The wire and magnesium flare had been placed in position so that a touch would set it off. With his Winchester close handy, Jim stood staring into the darkness and with ears strained to catch the slightest sound. The hours passed, but nothing came to disturb them. Then Ned's turn came. Thus the hours passed until Rogers relieved Ned for the last watch.

Rogers lit his pipe and smoked, as he, too, stared into the darkness. Once he thought he heard a sound, but put it down to his imagination; it may have been only the leaping of a fish or the lapping of the water against the rocks, or—

Flash! The rocks and lake were lit up as if by day, and on the edge of the lake, in the full glare of the blinding light, a ferocious-looking monster crouched. A warning cry from Rogers brought the two boys to their feet, blinking and rubbing their eyes in the unaccustomed light.

For a moment they saw nothing. Then the full meaning of the alarm burst upon them. There on the rock at the lake's edge, crouched a creature of forbidding aspect.

Bewildered by the unaccustomed light, it stood apparently helpless. Rogers was correct in his surmise. It was in truth a Birdman. Massive shoulders supported wings that dropped to the level of the rock. Its arms had webbed claw-like hands; from its feet two great toes protruded, and web connected the other three. The creature's shining fleshless skull was surmounted by a spike which gleamed like ivory. Underneath a broad forehead, from a ghastly face, strangely human, a pair of black piercing eyes glittered. The head was hunched between the great wings, the chin rested on a breast covered with black hair, and the arms and lower limbs were hairy.

The three wanderers shuddered at the sight of this uncanny denizen of the caverns. Even Rogers, the man of steel, was shaken to the marrow. Ned and Jim involuntarily clutched each other's arms. They, like the creature before them, stood spellbound. As they gazed, the seconds seemed like minutes. The tension grew past bearing—then a strange thing happened. The creature's eyes seemed to sway from one to another. Then without warning, the great body quivered, its legs sagged and a spasm of anguish flickered across the white face as, with a sigh of human pain, it sank inertly to the rocky floor.

Then without hesitation, he approached the stricken creature who, passive on the rock to which he had fallen, watched with wavering eyes the three human beings confronting it.

Rogers bent down and touched the creature. It did not flinch. He lifted one of its shaggy arms and held it for a few moments, then placed it gently down by the creature's side. In those few moments he had felt a weakening pulse.

"Boys," said Rogers, "this Birdman is weak from starvation. He comes not as an enemy. In his extremity he is seeking our help; timidity presumably preventing him from making his urgent appeal before exhaustion caused collapse. Hand me the first-aid kit, Jim; we will see what can be done to brace him up."

Deftly mixing a reviving draught, Rogers held it to his patient's lips. It was accepted readily. Only a wry spasm flitted across the white face at the unaccustomed taste of the liquid. The drug had immediate effect; animation came to the dull eyes, and to the inert body, renewed life. Rogers regarded the result of his ministrations with satisfaction.

"That pulled him together," he remarked. "Now let us see if we can induce him to eat."

Some excellent cold fish, the remains of the previous evening's repast, was produced and a small portion placed within easy reach of their strange visitor.

Slowly a claw-like hand was extended and a fragment of the food was taken between the finger and thumb.

That the diet was familiar soon became apparent. Before a morsel was conveyed to the lips, the fish was carefully dissected for bones, and only after being satisfied that it was quite free from them, was the food conveyed to the mouth. Without hurry, quietly and deliberately, the food was partaken of.

Rogers looked on critically. He knew that the creature before him was on the verge of starvation, and he was amazed at the restraint imposed upon what must have been an irresistible inclination to devour the food as speedily as possible. No aristocrat could, under the circumstances, have toyed with his food as this mysterious denizen of the caverns.

As Rogers watched, his face cleared, for a weight was lifted off his mind. The creature before him was unconsciously demonstrating that it had the power of reasoning. It was conversant with certain laws which governed nutrition of the body. It ate slowly, deliberately and ceased eating before the one-third of the food had been consumed. Then its eyes turned towards the lake. Rogers interpreted the look at once. It wanted water. A mug was filled and placed in its hand. The same restraint in drinking as in eating was shown. The water was slowly sipped until a third had been imbibed. Then the mug was placed carefully upon the rock.

An hour passed during which the three had discussed the circumstances leading to their acquaintance with the Birdman.

The new arrival was, of course, to them an unknown quantity, and although their immediate fears had been allayed, still, the situation was uncertain until they could become more closely acquainted with their visitor. Whether this was possible, they could not yet determine.

As an ally to help them on their way through the caverns, his help would prove invaluable. That such help was needed could not for a moment be denied. Perhaps their ultimate fate was in the keeping of that strange figure crouching on the rock at their feet.

As they talked, a movement of the Birdman arrested their attention. He seemed to be preparing to make some effort. His long arms were braced on the rock beneath him; they could see the corded muscles rise, as he let the weight of his body rest upon them. Then, with the ease of an acrobat, he rose to his feet. For a moment his great wings outspread, but were immediately folded again.

Then, after a fleeting glance at his benefactors, the Birdman turned to the lake, and, with a sudden plunge which scarcely made a ripple on the water, disappeared beneath the surface.

Unfeigned astonishment at the sudden action of the Birdman was depicted upon the faces of the three onlookers. Jim was the first to recover. His sense of humour was not to be denied.

"Chief," he said, with assumed concern, "see if he hasn't pinched your watch. Just like some of Ned's friends. You invite the beggars to dinner and they get away with the silver."

"My watch is all right," laughed Rogers. "But just wait a minute, Jim; I have a better opinion than that of our Birdman. I thought so," he ejaculated.

Rogers was intently watching the surface shown in the rays of the light. A ripple broke the surface; it came twinkling in towards the rocks; then, when the undulation reached the rocks, the head of the Birdman reappeared. His body followed, and, presently, without a sign of water on his wings and body, he stood again before them. Both arms were outstretched and each claw-like hand held a glistening, wildly struggling fish.

Promptly perceiving in the Birdman's action a desire to make some recompense for the kindness shown him, Rogers exclaimed: "By Jove, boys, he has brought us a love offering. The beggar is trying to show his gratitude for our help."

Rogers advanced and accepted the offering. The Birdman's eyes lit with pleasure at the understanding shown by Rogers, who, first pointing to the Birdman, indicated the direction of the camp where the fire still glowed.

Rogers' signs were clearly understood. The Birdman instantly started to walk across the rocks towards the fire, showing not the slightest fear when they arrived, but squatted down and stretched out his hands towards the genial warmth.

The Birdman's actions proved conclusively that he was quite familiar with the use of a fire. This was enlightening, and opened up a wider field for thought regarding future happenings.

As he squatted near the fire, from time to time the Birdman picked up small fragments of stick and tossed them into the flames, and when the supply was exhausted, his eyes roved round the camp, apparently in search of fresh fuel.

His audience watched intently. Presently he located the wood pile. Rising, he went to it and secured a supply with which he replenished the blaze.

"Ask me something easy," replied Ned. "Unless," he added, "he is getting a good hot 'un ready for you. I believe, you beggar, you are at last going to get your desserts."

The weird figure of the Birdman, crouching before the fire, had suggested to Ned's fertile imagination a scene from Dante's Inferno. That it should be staged for Jim's special benefit was, of course, in Ned's opinion, the natural sequence.

But the Birdman's active interest in the replenishing of the fire was not actuated by any personal interest in Jim's supposed lapses from the straight and narrow path. He had another and perfectly utilitarian object in view.

Rogers, himself, was puzzled by the re-building of the fire, for the atmosphere was comparatively warm. Then the real reason dawned upon him; the Birdman must want to cook the fish he had taken out of the lake. Rogers was intensely curious as to what method he would adopt.

Selecting a straight stick from the heap, the Birdman placed the thin end in the fire and waited until it became well alight. Then he rubbed the flame out on to the rock and continued rubbing the charred end until he had a fairly sharp point. Then, picking up a fish, he dexterously spitted it through the centre and treated the second in the same manner, afterwards placing the spit across the rough stones which formed the temporary fireplace.

Jim watched entranced, then, heaving a sigh of mock relief, he looked covertly at Ned.

At this pointed thrust, Ned snorted. Jim had touched his weakest spot, for Ned was the official camp cook, and, like all chefs, extremely sensitive to aspersions cast upon his capabilities.

Unaware that his culinary activities had caused a breach in diplomatic relations between two of his audience, the Birdman continued to turn his spit with the air of one who knew his job.

It was not difficult for his audience to realize that the Birdman was performing a function which he had exercised many times before, and was preparing the staple diet of the inhabitants of the caves.

When the cooking operation was completed, the Birdman glanced at Rogers and back to the spit.

Rogers understood they were invited to share the repast. Prompted by curiosity he placed four plates on the rock by the side of the Birdman, who looked at the array in perplexity, until Rogers demonstrated.

As the Birdman was taking the spit from the fire, Rogers held up a plate and shook a fish from the spit upon it, and held out another empty plate for the other fish. The Birdman's gaze wandered from the full plates to the empty ones. He was obviously puzzled.

"The beggar is trying to work out a problem in arithmetic," Jim whispered to Ned.

"For the love of Mike, don't you chip in or else he will get the answer wrong every time," came the ready answer from that aggrieved camp cook.

But the Birdman's reasoning powers were not sufficiently developed to suggest how to fill four plates with only two fishes and Rogers solved the problem for him, but cutting them in halves and placing a portion on each plate. The Birdman watched the operation, but when it was completed the expression of puzzled wonder remained.

"I never thought that the Chief would do a thing like that," whispered Jim. "We must have a word to say on this subject later on."

"Can't you see that the Chief has deluded the poor chap into the belief that he has performed a miracle by making two fishes into four," he explained.

Ned grinned. Jim's ready wit had found a loop-hole in Rogers' armour and it would not be the fault of the two young reprobates if they did not take full advantage of the position when a favourable opportunity arose.

Meanwhile, Rogers helped the Birdman out of his dilemma by handing him a plate, then disposed of the others between Ned and Jim and himself.

A glint of enlightenment shone in the Birdman's eyes as a result of this arrangement and, without further ado, he commenced to eat.

The early hour at which the boys had wakened made them feel drowsy, and, after they had partaken sparingly of the fish provided by their strange visitor, they rolled themselves in their blankets. Leaving Rogers to stand the remainder of his watch with the Birdman for company, they were soon deep in healthy slumber.

CHAPTER XIII. — WATERS OF DEATH

ROGERS was amazed at the recuperative powers possessed by the Birdman. A few hours previously he had sunk down on the rocks exhausted, yet, after a tonic and some food, he had recovered sufficiently to plunge into the lake in search of fish.

Why, wondered Rogers, had the Birdman starved when the fish were at his disposal in unlimited numbers?

The answer came when Rogers called to mind the episode of the cooking of the fish. The Birdman would not eat raw food, and being without means of making a fire, had, in consequence, suffered the pangs of hunger until it had driven him to seek their assistance. Such was the trend of Rogers' thoughts as he stood the last hours of his watch.

While the boys slept soundly, the Birdman sat crouched with his back to the cavern wall, but whether he was asleep, Rogers could not determine. While gazing at the crouched form, Rogers decided that, for the present, he would not divulge to the outside world that they had found the Birdman. Rogers felt that the story of the meeting and a description, of the uncanny creature found in the cavern would not be believed even were it supported by his two companions. The story would be under suspicion of having emanated in brains deranged by their enforced imprisonment in the darkness.

Yet it was true. For a moment Rogers faltered at the terrible possibility that perhaps the Birdman was a phantom conjured up by their diseased fancies. A cold sweat gathered on his brow. With recovering composure, he strode to where the Birdman crouched. Real! Yes, he was real. He could see the regular rise and fall of the muscular chest as the Birdman slept. Looking at the slumbering creature, Rogers was convinced that there was no doubt regarding his reality.

Rogers turned away abruptly. He had allowed doubt to assail him and an impulse that was irresistible had taken him to the Birdman's side. Rogers smiled grimly, for he pictured the consternation of the people of the outer world, should fate decree that the creatures of the caverns be thrown among them. He began to understand the reason why the secret of the caverns had been guarded by the Aboriginals. He and his companions had entered a forbidden domain.

He had not heeded that warning, and the mountain had shaken and crumbled behind them, cutting off all hope of retreat. Then, from out of the darkness came a being of another world, evolved when chaos reigned, and still, after the centuries, retaining his original form.

Rogers tried to visualize the community life of the race to which the Birdman belonged, but was unable to arrive at a satisfactory conclusion. Time would, no doubt, solve the problem, if they were lucky, or perhaps, unlucky enough ever to meet the people of the caves.

The arrival of the Birdman added another weight to Rogers' responsibility. The disposition of their weird visitor was an unknown quantity. Although first impressions indicated that he was comparatively harmless, it would be unwise to take too much for granted; therefore careful watch must be kept over his movements until they were satisfied that there was nothing to fear from him.

Rogers looked at his watch. The sun must now be shining on the mountains overhead, and the sleepers began to show signs of awakening.

Ned was the first to bestir himself. As he awakened he glanced lazily around the circle of light thrown by the spotlight, and presently the crouching form of the Birdman came within his focus.

Rogers, who was observing him, noted the perplexed look upon Ned's face and smiled grimly.

"He is real all right, Ned," he said. "I had my own doubts during my watch regarding his reality, but you can rest assured that he is not an apparition."

"By Jove, Chief, I thought I was dreaming," Ned confessed with an embarrassed grin, as he arose and joined Rogers.

A lazy voice, which apparently filtered through several layers of blankets, came from the direction of Jim's resting place and forestalled Rogers' reply.

Further discussion regarding the disposal of the Birdman was arrested by the actions of the subject of their conversation.

The Birdman arose slowly and ambled towards them. Half-way he stopped and his observers noticed that, although he was looking in their direction his gaze was not upon them, but was fixed upon something immediately behind.

Rogers and Ned turned involuntarily and Jim sprang hastily out of his blankets, but nothing unusual could be seen within the radius of their limited vision.

Pausing only for a moment, the Birdman went quickly to the lake's edge and stood looking at the water which lapped the rocks at his feet. Then he turned and moved his arms as if beckoning them to join him.

Wonderingly, they obeyed. The Birdman seemed strangely perturbed. Crouching down, he placed his claw-like hand upon the side of the rock half-an-inch above the water, and waited motionless.

As Rogers watched him, enlightenment came. The lake was rising. The water was creeping up the rock towards the Birdman's hand. As it touched, the Birdman straightened and, looking towards the cave's roof, threw his arms upwards.

The gesture brought home to Rogers with full force, the dangerous position they were in. If the lake rose to any great extent, they might be trapped.

The boys also sensed the impending danger. Turning towards them, Rogers said in a reasoning, matter-of-fact voice:

The Birdman's succeeding actions were now followed with absorbing interest. Leaving the lake's edge, he went to the fire and replenished it with a liberal supply of firewood. He did not choose all dry wood, but used also some which was slightly damp. This produced a smoky fire from which wreaths curled upwards and blended with the darkness of the cavern roof. Satisfied with the result, back to the water's edge the cave-man ambled, and, without hesitation, plunged noiselessly in.

The three explorers looked inquiringly at each other. The same thought was uppermost in their minds.

They had not long to wait for an answer to their unspoken question, for the Birdman reappeared within a few yards of the rocks.

"The beggar is fishing," said Ned, who had observed a wriggling fish in the Birdman's clutch.

Landing, the Birdman made direct to the fire. Picking up a sharp stone, he neatly split the fish open, cleaned it, and, spitting it, he placed it where the smoke was thickest. Once again he plunged into the lake.

Rogers was the first to perceive the significance of the Birdman's efforts towards laying in a supply of food. That he had knowledge of curing by the smoking process, was evident by the workmanlike manner in which he performed the operation. The fish so treated, even without the use of salt, would keep longer. As a demonstration of intelligence, it proved that the Birdman had a brain capable of reasoning. To what extent of development it had reached, only the future could determine. In any case, the Birdman was setting them an example which they would be wise to follow.

"Get your lines out and catch as many fish as possible before the lake rises too high," Rogers directed. "Our friend knows these caves, and we cannot do better than follow his example and make preparation against emergency."

The fishing went on until the Birdman seemed satisfied that sufficient had been provided for future requirements. Every fish was carefully smoke-cured.

"He has safeguarded himself against starvation for some time," remarked Rogers as he surveyed the result of the Birdman's industry. "Evidently these caves are subject to serious floods and he has acted upon knowledge previously gained. Mentally I have compared this cave and lake with the others we have negotiated. This roof is much lower, which means that if a heavy flood occurs the water may fill it completely. So, lads, the best thing we can do is to pack up and move on in the hope of finding a loftier cavern. It is our only hope of escape if a flood does come. The lake is rising rapidly and soon these rocks on which we are camped will be under water."

Work was at once commenced. The boat was launched and the camp gear stowed aboard. The Birdman watched the preparations for departure with eager eyes—it seemed as if what they were doing merited his full approval. When all was ready to push off, the caveman entered the water and swam slowly away from the rocks.

"Push off, Ned," said Rogers, "he intends to pilot us. God knows we want a pilot," he thought, in realization of their dire peril. Aloud he continued: "I feel sure that we can trust him, so we will follow his lead."

Manipulation of the paddles sent the boat in the wake of the Birdman, who, perceiving their intention to accept his guidance, swam steadily onward, occasionally turning his head to make sure that they were following. As they progressed, they realized that the lake was rising so rapidly that the roof seemed to be coming down to meet them.

Suddenly the Birdman ahead splashed the water violently. When he saw that he had attracted their attention, he darted off at redoubled speed.

"All right, Chief," came the cheery response, and the blades flashed as the boys put their weight on. The black water slid by with increasing swiftness. Dip—dip—went the blades. Lower, ever lower, came the menacing roof, until they might have touched it with their paddles. Swaying to the rhythm of the paddle strokes, Rogers watchfully played the spotlight on the roof and on water ahead. The air was strangely oppressive, and breathing became difficult. Rogers knew that this was caused by compression of the atmosphere by the rising of the water. The boys began to feel the strain, yet they paddled doggedly, with set faces. They knew that they could not continue much longer. Rogers watched their distress with agonized eyes. Dip—dip—their strokes became mechanical. The lowering roof seemed about to fall upon them. Rogers sat tensely waiting for one or the other to collapse. He was ready to spring to the paddles at a moment's notice, but no good purpose could be served by a change at such a critical moment. Ahead, the roof seemed to touch the water. This, then, was the end!

As this thought welled uppermost, the water was cleft by the body of the Birdman swimming like an otter in the direction of the boat. As he reached it, he turned swiftly. A hand darted out of the water and grasped the painter which had been trailing from the bow. With incredible strength; he took them in tow. The boat moved so swiftly that the tired arms of the boys could not make any impression on the water. Thoroughly exhausted, their heads fell forward over their knees with their paddles grasped in nerveless hands. Rogers himself was in not much better case. His lungs seemed to be bursting. Their fate was in the hands of the Birdman. If he failed to reach a loftier cavern within a few short minutes . . .

To the stout-hearted Rogers, oblivion came. A violent blow sent him sick and reeling to the bottom boards, just as the boat, with only a few inches to spare, emerged into a spacious cavern. But the danger was not all over. The great volume of water whose only outlet was through the lower caverns, created a mighty whirlpool, and only the superhuman efforts of the Birdman prevented the boat and its exhausted occupants from being drawn into the vortex. He was only just holding his own against the current, for he was handicapped by the tow-rope which deprived him of the services of one arm. Surely the grip of the water became stronger. The Birdman began to lose ground. Slowly the boat began to drift towards the whirlpool. Only a miracle could save them from destruction.

Since they had emerged into the purer air of the larger cavern, Rogers had shown signs of returning consciousness. Unwittingly, he moved a hand which came in contact with the terminals of the battery supplying current for the spotlight. The result was instantaneous, for the shock galvanized him to full consciousness. A hasty glance around showed him the peril with which they were threatened. Seizing a paddle, he plied it with all his strength, pausing only for a moment to splash some water over the boys' heads, with the hope of reviving them. The cold water and improved air conditions had the desired effect on both boys, for Ned and Jim revived sufficiently to take an interest in the proceedings.

The result of Rogers' superhuman efforts was now apparent. The boat's backward drift was averted. It needed but a united effort to gain upon the current. Jim seized his paddle and Ned, now fully recovered, also took his from Rogers' hands.

The boat began to gain headway. Slowly they won out of the danger zone, guided by the Birdman, who, still holding the tow- rope, swam in the direction of the cavern wall.

The spotlight revealed a rocky projection rising abruptly from the flood waters. It was quite flat on the top. If they could get a footing upon it, they would be safe, unless the flood rose still higher. Reaching its base, they found that they were out of the set of the current. The Birdman, first to reach their haven, clambered up. With gratitude in their hearts for the gallant help of their newly-acquired friend, they followed, first taking the precaution to secure their boat so that it would not be in danger of being stove in by contact with the rocks. A long kellick was paid out astern and a lengthy mooring rope was passed up to the top of the rock. This done, they had time to examine the extent of Rogers' injury. Blood was flowing from a nasty cut above the temple made by a projection from the roof. The first-aid was brought into requisition, and the wound skilfully dressed by Jim.

But the danger was not all over. With anxious eyes they watched the ever-rising water until they feared they would again have to seek refuge in their boat. When hope had nearly gone, and they were preparing to embark, the water ceased to rise. For a time it remained stationary. Then it began to subside. The falling of the flood raised their drooping spirits. It was like an eleventh hour reprieve for men condemned to die.

After their trying ordeal rest was necessary, and, satisfied that the danger had passed, Rogers gave orders for making camp. A fire was soon blazing, made from wood brought in the boat, and, thankful for their escape, the explorers partook of a comparatively cheerful meal. Their deliverer, from whom not a sound had been heard, crouched by their side and ate sparingly of the cooked fish which, thanks to his forethought, had been provided. Then, wearied out, they slept. No watch was kept, for confidence in their strange deliverer was established. They knew if evil were to befall them, it would not be at the hands of the Birdman of the caverns.

Hours later, the sleepers awoke, refreshed by their rest and able to concentrate upon the problem of escape. From their resting place, the spotlight enabled them to survey their surroundings for a considerable distance. To their astonished eyes, a scene quite different from any previous experience in the caverns was revealed.

The flood waters had subsided and their boat lay high and dry, resting on an even keel. Instead of a broad expanse of water which characterized the caverns through which they had passed, they saw a maze of small islands, between which channels ran in every conceivable direction. These miniature islands were so close together that navigation was likely to be extremely difficult. The water level was many feet below the summits of the rocks, which would make it difficult to maintain any definite course when traversing the labyrinth. Within that network it was possible to become hopelessly lost. How far this maze of channels extended could not be determined even from the lofty position from which they viewed the disconcerting scene. Perhaps the open system of lakes had come to an end. If this were so, their rate of progress would be considerably curtailed.

Rogers, who had recovered from the blow on his head, gazed with no little concern upon the unexpected obstacles which beset their path.

Then he bethought himself of the token. It might throw some light upon their problem. Procuring it, he examined it carefully.

CHAPTER XIV. — THE DEVIL'S MAW

DURING previous examinations of the token, the underground wanderers had been puzzled by a number of crossed lines which appeared on a section of the lake area. This section was of considerable extent and deviated from the westerly trend of the chain of lakes by branching off towards the northwest.

"This is our present position," Rogers said, placing a finger upon these lines. "The crossed lines indicate the islands and channels which we see before us. Whoever carved the map on the token must have had a strenuous task in threading this confusing labyrinth. His difficulties were greater than ours, for fortunately we have lights to aid us, without which our chances of getting through would be slight. Our predecessor must have wandered over the greater portion of this lake of islands before finding a way out, as the details in his map prove."

"Our best plan will be to traverse the southern side of the lake, keeping as near as possible to the cavern wall," he said. "The shores on the south side appear to run comparatively straight, whilst to the north-west it looks as if we would find ourselves in a blind alley if we follow that route."

Ned and Jim, who had closely followed Rogers' reasoning, agreed that their best chance of finding a way through the maze would be by the southern side.

"We cannot afford to waste time," Rogers continued after the point had been settled. "Our batteries are getting low and it is necessary that we find running water in order to recharge them. We must do our utmost to push our way through before they give out. From now on, we must economize and use the spotlight only when absolutely necessary. But we have forgotten our friend the Birdman. If we can make him understand where we wish to go he may guide us through the tangle."

At the mention of the Birdman, Ned looked round. They had been so completely absorbed in discussing their whereabouts and planning their advance, that, for the time, they had forgotten his existence. After scanning the rock and its immediate vicinity, Ned said in surprise: "The beggar has disappeared."

The disappearance of the Birdman came as a shock to the trio. The few hours he had spent in their company had been momentous ones. They had passed safely through the terrors of the flood only by the Birdman's timely aid, and now, having rendered them a signal service, he had gone his way. The realization that he had left them seemed to make the caverns darker and more menacing. The help he had rendered in their extremity during the flood had raised a hope that the Birdman might be able to guide them past the formidable obstacles confronting them.

The Birdman's absence caused a vague feeling of disquiet, and they looked questioningly at each other. Rogers broke the tense silence.

"I don't think that he has deserted us. I feel sure that we shall see him again. There is one factor which we must not overlook, that is food. In all probability we would not have made his acquaintance had he not by hunger been impelled to seek our aid. Our camp fire was the magnet which drew him. He could not previously subsist on a diet of raw fish and he cannot do so now; therefore, sooner or later we may expect him again to put in an appearance. Unless," Rogers qualified, "he has taken fire with him, which is unlikely. It may be that we are getting near to the community from which he came, and he has gone on ahead to pave the way for our reception. This view is quite feasible, but the question arises why the Birdman should be wandering alone in the darkness if the way was open for him to return if he so desired. The only explanation I can suggest, is that he was banished for breaking some tribal law or custom, and the door, figuratively speaking, is closed for ever against him. If this is the case, our Birdman may be risking his life on our behalf. On the other hand, he may be searching for a passage down this terrain archipelago through which we can take our boat. The only certainty is that we must rely on our own efforts to get out of the caverns, so let us make a start," he concluded.

Hours later, despite many miles of travel, they were still entangled in a network of channels. They had started off down a fairly straight water lane on the southern side. Soon it turned at a right-angle, later to twist towards the east, the way whence they came. There the walls confining the channel they followed became broken, and led them to a shoal studded with pinnacles, with just enough room between them to navigate the boat. Some of the rocks were so close together that the boat barely scraped through. The fenders affixed by Rogers were of inestimable value. Without their protection the canvas shell of the boat could not have withstood the repeated collisions with the rocks. They realized, as never before, that preservation of their lives depended upon the staunchness of their little craft. Should destruction befall it, only a miracle could save them.

Their tortuous course necessitated almost continuous use of the spotlight and Rogers noted with concern that its brilliance was slowly diminishing and soon they would be in utter darkness. The prospect was alarming. When the light failed, they would have only their limited supply of magnesium ribbon and powder to depend upon. They must grope their way through the darkness as best they could.

Since embarking on this stage of their journey, they had been unable to light a fire. The precipitous rocks afforded no footing. There were no ledges upon which they could land for a rest, so perforce they remained in their boat. Sitting uncomfortably hour after hour in the confined space, their limbs became cramped, and their eyes ached intolerably from the strain imposed upon them in an endeavour to pierce the inky darkness.

Presently the spotlight failed, and night eternal seemed to close upon them. Doggedly they groped amid the rock-strewn waters for a channel which would lead them back to the southern wall of the cavern, along which, they felt instinctively, lay the way out. Since taking their departure they had been gradually forced in a north-westerly direction, and it seemed inevitable that they would eventually find themselves cornered in the blind pocket depicted on the token. Many were the turnings made to the west and south-west, only to find, after a short distance had been traversed, another rock wall ahead with the unavoidable turn to the right.

The north-west drew them like a magnet. Then, sick at heart, with repeated failures to make progress in the desired direction, a rock was discovered upon which a foothold could be obtained. From its base just above the water a shelf jutted. It was of sufficient size to allow the making of camp and to enable them to stretch their cramped limbs.

After their ordeal of the past hours, the discovery of this haven of rest came as a gift from Providence, and no time was lost in taking advantage of the opportunity of exchanging the frail support of their boat for a spell on solid ground. Presently, with a cheerful blaze illuminating the cavern in their immediate vicinity and having partaken of a satisfying meal, their spirits rose until even the gloom of their surroundings seemed to press less heavily upon them.

Reclining on their blankets with eyes focused on the glowing embers of the fire which seemed to be the only link between them and the material world, their thoughts reverted to the Birdman. Rogers reopened the subject. Thoughtfully pressing a finger into the bowl of his pipe, he gave utterance to the thoughts which were uppermost in his mind.

"Despite the disappearance of our winged acquaintance, I do not believe that he has deserted us. Possibly he returned to our camping place and found that we had gone. Assuming this, we can only conclude that he is now searching for us. In which case, we must do something to assist him. Our lights have failed, but we can still contrive to attract his attention to our position. I propose that we stand watch in turn for the next few hours and signal every half hour by means of magnesium. If he is in our vicinity, he cannot fail to see the flare, and if he desires our company he will come."

The experiment suggested by Rogers commended itself to his two companions, and the watches were arranged. To Ned fell the first, to Jim the second, and Rogers the third watch.

It was decided, however, to make a preliminary combined ascent of the rock. Provided with a torch and a spool of magnesium ribbon, they set off on their upward way. The ascent was easier than anticipated and they reached their objective without accident. The summit of the rock was comparatively level and in striking contrast to the spire-shaped pinnacles surrounding them. In eager haste Rogers produced the magnesium ribbon. Cutting off a foot of ribbon he inserted this piece in the split end of a stick which he carried for the purpose.

"This will burn for about six seconds," he said, as he struck a match and ignited the ribbon. Instantly a brilliant light illuminated their surroundings.

Standing back to back, every part of the cavern was within range of the explorers' combined vision. As with a final splutter the ribbon burnt out, a mental picture of their surroundings had been registered by each one of the trio. Separate, yet alike. Rocks! Nothing but gaunt rocks, age-old sentinels in the darkness girding the silent waters of the lake.

The prospect was not reassuring. It seemed impossible that they would ever escape from that tangled maze. Yet the possibility of having to abandon their original plan of exploring the caverns to their fullest extent did not occur to them. Should such an idea intrude, they would be faced with the same problem. It was by no means certain that they could find their way back if they wished to.

A thought flashed through Rogers' mind as the last sparks of the ribbon fell: sound travelled a long way in these underground caverns. A shot might be heard by the Birdman if he were too far away to see the glare of the light. Warning his companions of his intention, Rogers drew his automatic and fired it in the direction of the cavern roof. Its sharp crack could be heard reverberating through the caverns for some moments after. Satisfied that the position chosen for their watch-tower was the best available, Rogers and Jim descended to the camp, leaving Ned to wait and watch for the reappearance of the Birdman.

The first hours of tense watching brought no result. As the lights at measured intervals flashed through the darkness without response, Ned's hopes of attracting the Birdman's attention fell to zero. Suddenly a distant sound caused the lone watcher's pulse to quicken. Slowly, barely perceptibly, the sound increased and Ned's straining ears detected the direction from which it came.

If it were made by the Birdman, that person was flying in a gradually narrowing circle, probably searching every cranny and pinnacle in the cavern for them.

Confident that his long watch was about to be rewarded, Ned promptly lit a length of ribbon to guide the Birdman to their location.

As the light flared, Ned distinctly saw a moving shadow which, before the glare died, resolved itself into the Birdman. With the lightness of a feather, the missing man of the caves landed by his side. Overjoyed, Ned felt impelled to shake hands with the truant, but restrained the inclination, reflecting that such a demonstration might alarm the stranger. Imagine Ned's surprise when the Birdman placed claw-like hands on his shoulders, giving him what was intended to be a gentle pressure, but causing the receiver of the salutation to fear that his arms were leaving their sockets.

Ned subsequently confided to Jim that he would be willing to back the Birdman against Rogers for the heartiness of his grip.

There was no doubt about the Birdman's joy at finding them. Ned could sense it, although he was unable to see the face of their returned guide.

Uncanny though it seemed, a feeling of mutual trust had sprung up between that strange creature of the caves and the three humans who, by their call for aid, had put their lives in his keeping.

Remembering that the Birdman had been away for several hours and probably was hungry, Ned immediately, in clambering down the rock to the camp, awakened Rogers and Jim and told them of the return of the Birdman, who in support of Ned's story, dropped on the wing from the summit of the pinnacle and landed lightly before them.

They waited until he had broken his fast, then they sought their blankets to sleep and fit themselves for whatever perils might lie before them.

"Morning dawned" should be the natural sequence to the events just recorded, but in the caverns perpetual night reigned, so our adventurers awoke in the dark refreshed, and delighting in reunion with their friend.

Without delay, camp was struck and the journey recommenced under guidance of the Birdman, who took up his self-appointed task as soon as they were ready to start.

Entering the water, he waited until they got under way, then swam steadily a few feet ahead of the boat.

Deprived of the services of the spotlight, an occasional flash from a torch located the position of the Birdman, who, when a turn was to be made, came alongside and placed a hand on the bow of the boat and guided it into the desired channel.

By what devious ways he took them it was not possible to recall. Frequently he would leave the water and take to the air, and, after circling overhead for a time, would return and once more pilot them.

By his aid they won out of the tangle of rocks which encompassed them, and they found themselves on the southern side, where the way became comparatively free from obstructions. Thus they were able to keep a fairly straight course westward.

At length, after many hours, open water lay ahead. They had safely passed through what Jim succinctly described as "The Devil's Maw".

In his diary, Rogers does not dwell upon this stage of their journey. The way was so depressing that they named the waters on which they travelled the "Black River". They had sought in vain for running water, and it was only after hope had dwindled to zero that they found a stream which would serve their purpose of recharging their batteries.

After camp had been made Rogers rigged his water-wheel in conjunction with the dynamo, and, in addition to charging the batteries, they found it possible to keep a light burning.

While they camped they noticed the Birdman beginning to show signs of restlessness. Rogers was impelled to remark upon his strange behaviour.

"I think we are getting near to the community of the Birdmen," he said. "What our reception will be there is no means of ascertaining. Our friend seems worried, but whether it is on his own account or on ours is difficult to say. Watch him flying off, and after a short absence return hurriedly, as if expecting to find us gone. Perhaps we are in a locality visited by other Birdmen besides himself, whom he does not wish us to meet unless he is handy to avert a misunderstanding. There he goes on another excursion."

As they sat and discussed what the future might bring forth the light revealed the features of the two boys. The healthy coating of tan had disappeared. Their faces had assumed a pallor not many shades darker than the Birdman's. Rogers' skin also bore evidence of the effects of the perpetual darkness. Happily, their strength remained undiminished. Mentally and physically, the vigour possessed when first they entered the caverns was unimpaired. From long confinement the pupils of their eyes had become dilated, and the faculty of being able to see in the dark was being gradually acquired.

Their eyes no longer ached through striving to pierce the darkness, for they were aided by the reappearance of the nebulous light which had, in the earlier stages of their journey, illuminated their surroundings. Without the aid of their torches they were enabled to distinguish objects a considerable distance away. Thus the danger of a surprise attack from close quarters was minimized, should they meet an enemy.

It was well that nature had provided the three with strong constitutions, for even now they were on the verge of having their strength and resourcefulness put to the test.

The rocks on which they had pitched camp bordered a lake of considerable size. During their enforced stay they had explored it as far as practicable. They found they were camped on the southern end of a fork, the prongs of which comprised two great lakes or rivers, one running due west, the other to the north- west. This latter was not shown on the token. How far it extended they could not determine, but later events proved that it led to other great caverns within which they were destined to meet with many strange adventures.

Conversation had lulled somewhat, and Rogers arose and connected the receiving set.

They had kept in touch with their friends throughout and reports were received regularly regarding the progress of the attempt at rescue. The tunnel was being driven in as rapidly as the nature of the rock formation would permit, but care had to be taken to avoid a collapse, which was possible owing to the loose nature of the strata through which the workings passed.

Having connected the wires, Rogers resumed his seat beside the boys, when the announcer's voice was heard:

"Cave Station, stand by! We have an important message for you. Please reply if you get reception.

"Hello, hello. Information has just been received from the crater station that the mountain is again moving and that the workings by which it was hoped to reach you have fallen in. There were no casualties, as a shift had left the workings and another was about to go in. Keep your spirits up, for work has been resumed."

"Well, we have listened in to more cheerful news than that," Rogers commented at the conclusion of the broadcast. "As I expected, the old mountain hasn't settled down yet. How old Bal- yari knew that it was due for an attack of the shakes is beyond my comprehension. Well, boys, our chance of getting out the way we got in is not bright. It seems that our destiny is to go westward. Whatever befalls, we have two barriers, the Devil's Maw and Bal-yari's Mountain, behind us. We know of no obstacle ahead, so west it must be, or if we rely on Bal-yari's token, west and south."

Then Rogers devoted himself to a long talk with Mel, to whom he sent a cheery message, in which there were no forebodings as to the ultimate result of their adventure.

CHAPTER XV. — CANNIBALS OF THE CAVERNS

THERE were no marked changes of temperature in those underground caverns, yet the camp fire had an attraction hard to resist. It was not for warmth the three sat within the radius of its heat; the companionship of its cheery glow drew them.

In various attitudes they lounged. With elbows on his knees and with face cupped in his hands, Ned gazed at the sparks which flew upward; Jim lay full-length with elbow resting on the rock and a hand pillowing his cheek, thinking. Perhaps of Mel.

Rogers sat with his back to a rock, peculiarly occupied. Occasionally he looked up from his task and gazed steadfastly into the darkness, as if he were waiting for something to emerge from the shadows.

From quarter plugs of gelignite Rogers was making bombs, with short lengths of fuse meant for use at close quarters. Rogers was expert in the handling of explosives and his "little pills," as he called them, could be employed either to frighten or for more serious effects. They were easily carried in a pocket, ready for immediate use when occasion required.

Rogers had transformed six plugs of gelignite into twenty-four handy little bombs, when his attention was arrested by a slight movement of the water, such as would result from a quickly moving body just under the surface.

While he watched it approached the shore a few yards below the camp, where an isolated rock rose from the water. The movement ceased at the back of the rock, when the Birdman, screened from view of all except the occupants of the camp, emerged. Waist-deep in the water he stood, without attempt to approach the camp. Perceiving that he had attracted Rogers' attention, he pointed towards the north-west. Rogers quickly realized the significance of the Birdman's actions: he had contrived to reach them unseen to give warning of some impending danger which was coming from the north-west.

"Ned and Jim!" the boys heard Rogers say quickly. "Move with caution. There is going to be trouble presently. Our Birdman has just returned. He is hidden behind that solitary rock and is pointing to the north-west as if expecting an attack from that direction. Get the arms and ammunition ready, and the spotlight and magnesium for a flare. Do it as quietly as you can, then come over here and put your backs to the rock. I will cover you from the water's edge."

As he spoke Rogers slowly arose and sauntered towards the edge of the lake. In his right hand lay one of his newly manufactured bombs with fuse end on to a safety matchbox, with striking side upwards. In his left hand he held three safety matches.

In response to Rogers' sudden call for the spotlight, Ned turned the light on to the lake. A match flared and the boys saw a tiny cascade of sparks describe a segment of a circle as a gelignite bomb sped hissing towards an approaching disturbance which the keen eyes of Rogers had detected on the lake's surface. Two more bombs were thrown in quick succession, one each to the right and left, each punctuated by a dull explosion and a column of leaping water.

Almost concurrently with the explosions, black bodies rose like a shoal of leaping dolphins. Reaching the apex of their leap, great wings outspread and the void of the cavern became alive with flying Birdmen, who, in their leap from the lake, approached so close that the spotlight revealed that their faces were black. Momentarily amazed at the result attained by the use of the bombs, Rogers stood gazing at the dark shadows until they disappeared in the recesses of the cavern.

Although Rogers had only paused momentarily, he had exposed himself to a danger of which he did not become aware until he found two powerful arms encircling his body, his feet left the rocks and he found himself lifted and carried bodily through the air.

Up amid the gloom of the cavern, from a projecting ledge, a pair of brilliant eyes in a face of almost ebony hue watched every movement of the occupants of the camp. When Rogers sauntered to the lake's edge, the eyes gleamed with a malignant light, and the creature to whom they belonged tensed its body ready for the moment when it would hurl itself upon its intended victim.

The exploding bombs did not divert its gaze for a moment from the figure at the lake's edge. The rise of its fellows from the water seemed to be a signal to strike. With the speed of an arrow the huge body launched itself from the ledge. Its outspread wings beat momentarily, the head sank down between the great shoulders, leaving only the cruel spike visible, then the wings closed and a living projectile hurtled downward.

But keen eyes were watching for attack from overhead. From its shelter behind the lone rock, the creature who had befriended the wanderers saw the danger which threatened Rogers. He knew what to expect from that menacing figure crouched on the ledge above. With a mighty leap he took the air. With the speed of a hawk he turned and swooped down to where Rogers stood. His sinewy arms shot out, grasping Rogers by the body and lifted him clear of the rocks. The momentum carried rescuer and rescued to the shelter of the rocks from which Ned and Jim viewed the amazing scene. The Birdman's wonderful feat was accomplished not a second too soon; the dark body of the Blackface grazed them as he passed to soar again into the darkness, his deadly mission unfulfilled.

The disappearance of the Blackface meant only a temporary respite. This was conveyed by signs by the Birdman, who, with clarity of vision, could see through the veil of darkness which their sight could not penetrate. Placing Rogers on his feet beside Ned and Jim, he motioned them to take cover behind a rock which stood parallel with the cavern wall. This breast-high, flat-topped rock was used for the storage of camp gear, while behind it the boat was snugly stowed.

When they were safely under cover, the Birdman, looking at Rogers, made a gesture towards the northwest. Then he pointed to himself, and, after a pause, indicated his mouth.

Seeing that he was not understood, he again pointed to the north-west, then to each of the others in turn, and moved his jaws as in eating.

"He is remarkably excited; whatever is he trying to tell us?" Ned whispered to Jim.

Jim, also, was puzzling over the Birdman's actions. Failing to make himself understood, the Birdman, suddenly taking Jim's hand, made mimic motions of masticating it.

"I've got it!" Jim cried in sudden comprehension. "Chief, our Birdman means that the Blackfaces eat flesh and are cannibals."

"Yes, Jim," assented Rogers, who had also interpreted the Birdman's signs. "I am afraid that is what he has been trying to tell us. If such is the case, we must use every means of defence available, for they would show us no quarter if we fell into their hands. If they attack again, we must be prepared to give them a warm reception. Our only chance is to prevent them from getting to close quarters. In a hand-to-hand fight, we would be no match against their greater numbers."

Ned switched on the spotlight and searched the cavern within the limits of its power. A dozen dark forms were seen circling in front of their position. As the circle narrowed, they gradually drew nearer to the watchers, until they passed within a stone- throw from the rock.

"Do not fire unless they attack," warned Rogers. He had hardly spoken when the leader headed straight towards them. He was seen by Ned to make a peculiar movement of the body.

"Down!" Ned shouted, as something whizzed by and struck the cavern wall a shattering blow.

Rogers' automatic spat viciously, but the bullet went wide; Jim sighted the Winchester on the next Blackface and pulled the trigger. He too missed his mark, and another missile hurtled by. They continued to circle, and as each in turn passed a missile was launched, luckily without taking effect, although the rock behind which they sheltered was frequently struck.

Becoming more daring, the Blackfaces came in closer. Their daring led to their undoing, for Rogers was only waiting for their nearer approach when he would spring a surprise upon them. He had been busy shortening the fuses of his bombs that they might burst during their flight. Now the time had arrived to use them. Carefully judging time and distance, he threw a bomb across the flight of a Blackface, which burst when the latter was about to hurl his missile. The noise of the explosion in a place where even a whisper created an echo was terrific. It struck the ear- drums like a blow, and it rolled away down the caverns until it seemed to die away in the distance, then back it came, gradually increasing in volume as it drew nearer, until the cavern in which the explosion took place was again filled with a mighty roar. Terrifying—uncanny—it seemed as if all the demons of the underworld had been let loose, to rage back and forth, bellowing in fury at being baffled in their attempt to escape the confines of the caverns, to return to their lairs at last with ominous mutterings.

Stayed in their flight by the bursting bomb, panic seized the attackers. The leader, being nearest to where the explosion occurred, felt its effects in a greater degree than his companions. Driven down in what Ned afterwards described as a nose-dive, he hit the water before he had time to straighten out. He was not allowed to ponder over the cause of his downfall, for another bomb drove him out almost as quickly as he had entered, to take flight in the wake of the retreating Blackfaces who had already vanished in the darkness.

The failure of the attack was hailed with relief by the defenders of the camp. The salutary effect of the bombs on the Blackfaces proved that they had a weapon of inestimable value with which to combat any further attack. But it would not be wise to remain in their present position, for the Blackfaces, after recovering from their bewilderment at the unexpected reception they had received, might return in greater numbers, perhaps reassured by the fact that none had received any bodily injury.

This view was voiced by Rogers, who intimated that they must immediately strike camp and continue their journey west.

The Birdman, although startled by the explosion, had not shown any fear, yet seemed anxious to be moving on. He repeatedly pointed to the north-west and thence to the west, augmenting his signs by walking a few paces in the direction he pointed. It was not possible to misunderstand his meaning. He feared that the Blackfaces would return.

Camp was struck and they were ready to embark. Their batteries were now well charged, and they were setting off with greater confidence than they had felt when leaving their last camping place. When striking camp, an important discovery had been made by Jim. While giving a last look round to see that they had not left anything behind, he discovered lying at the base of the cavern wall a number of the missiles which had been thrown by the Blackfaces. Calling attention to his discovery, the weapons were eagerly examined.

The surprise they felt when they realized that they were handling weapons fashioned out of metal was manifest on the faces of both Ned and Jim. In shape resembling a club, the missile consisted of a heavy bulb welded to a slender handle—a most formidable weapon if thrown or wielded at close quarters.

"If the Blackface who tackled me out there on the rock had used one of these instead of trying to impale me on his spike, the result of the skirmish might have been different," he declared. "Anyhow, I have to thank our friend the Birdman for pulling me out of that scrape. This find of Jim's is of great importance, because it indicates that the inhabitants of these caverns are not lacking in knowledge of at least one of the arts. If they are conversant with metal working, they may be also advanced in other respects."

Turning to the Birdman, he extended the club. Taking it, the Birdman twirled it rapidly between his fingers and thumb before he sent it hurtling towards the cavern roof.

Intently he watched the club rise, and when, losing impetus, it fell, a hand shot out and grasped it before it reached the rock, convincingly demonstrating the Birdman's keenness of sight, and his dexterity in manipulation of what, evidently, was a familiar weapon.

CHAPTER XVI. — A FIGHT FOR LIFE

PRECEDED by the Birdman, they continued their journey westward. Each had selected a Blackface club, the Birdman retaining the one handed to him by Rogers. The others were thrown into the lake out of reach of the marauders should they return.

As they progressed, the Birdman regularly made scouting expeditions rearward, evidently expecting pursuit, but hour after hour passed without any further attempt being made to molest them. They were travelling upon a wide expanse of water, keeping close to the southern shore in preference to the open water of the lake. If an emergency arose, they could more easily land, and, with their backs to the cavern wall, stand a better chance of beating off their enemies than if they were on the more exposed waters of the lake.

At intervals camp was made, no difficulty being found in selecting suitable landing places.

The nebulous light was still manifest and made their journey easier, but once again the monotony seemed to sap their energy, until they felt that even the reappearance of the Blackfaces would be welcome.

But the end of their present journey was much nearer than they anticipated. Following an unusually long stage, camp had been made, and after they had partaken of food, the Birdman, by signs, intimated that they were to remain while he went on ahead.

When he saw that they understood, again using signs, he directed them to keep watch in the direction whence they came. Then without further ado he set off.

As they sat in the semi-darkness, for they had been compelled to dispense with the luxury of a fire since they had started on their journey from the scene of the attack by the Blackfaces, the conversation turned on the Birdman.

Ned remarked upon the fact that since they had met him, he had not spoken in their hearing.

"But you cannot fail to have noticed that when we are speaking he listens with apparent interest."

"That is so," Rogers agreed. "His failure to talk does not imply that he is not capable of expressing his thoughts orally. It may be due to some other reason. I still believe that he has been ostracized from his tribe. It may be that his silence is due to loyal acceptance of the punishment imposed upon him, which perhaps is banishment with a pledge to silence until the term of the sentence expires.

"I have known primitive peoples with a code of honour so strong that nothing would induce them to break any bond to which they had given their assent. The community to which the Birdman belongs may have such a code, and if our Birdman has infringed some law, and his punishment is what I suggest, we can vouch that he has strictly adhered to at least one clause of his bond.

"The Birdman's departure westward suggests that, anticipating attack, he has gone for assistance," Rogers went on. "The Blackfaces we encountered were probably scouting ahead of the main body. The latter may possibly not believe the report that strangers helped the Birdman to repel the attack of the scouts, and continue to advance. Whether my theory is correct or not, we must be prepared to make a stand should the Blackfaces attack before the Birdman returns. Now let us make ready to move on at a moment's notice."

Both boys agreed with the view taken by Rogers of the position, and it was decided to have the boat ready loaded in case of emergency.

Camp had been pitched under an overhanging rock with a natural breastwork between it and the lake, similar to the position occupied when they successfully repulsed the Blackfaces. More bombs had been prepared, and Ned and Jim instructed in their use, Rogers insisting that they must first practise with a piece of fuse tied to a stone. Both soon became so proficient that Rogers was satisfied that as bombers they would give a good account of themselves should necessity arise.

Final details of defence were completed by setting a flashlight signal a quarter of a mile to their rear. A small raft was fashioned out of two logs fastened together and connected by a length of cord to floats moored on either side. The floats were about a hundred yards apart, with the raft in the centre. A charge of magnesium was placed in position, with a cunningly contrived arrangement for ignition, which operated when either of the connecting lengths of cord was disturbed. A gelignite bomb was also attached so that it would explode with the ignition of the magnesium if the Blackfaces elected to attack by way of the water. It was more than possible that they would fall foul of the cords, and thus warning of their approach would be given.

Having done everything possible to guard against an attack, there remained nothing to do but await what the ensuing hours might bring; but vigilant watch would have to be kept to prevent a surprise.

The Birdman had not returned, but they knew that he would not fail them unless he was detained by some unforeseen circumstances.

Conversation had ceased, when the watchers, almost hypnotized into slumber by the silence and continuous strain, sprang to their feet.

A blinding flash had lit the cavern, and at the same instant an ear-splitting explosion told them that the Blackfaces were again approaching.

"Quick with the spotlight, Ned!" Rogers commanded. "If we have to shoot, it must now be to kill. We must not allow a Blackface to land. If they gain a footing fight to the end but," he added significantly, "DO NOT BE TAKEN ALIVE!"

Ned and Jim understood perfectly the reason for Rogers' significant warning. Without replying, in turn they gripped his hand in a clasp of true comradeship, whose pressure conveyed a message that could not be expressed in words.

Swiftly they focused the spotlight on the scene of the explosion. The distance was too great to allow a distinct view of the surroundings, but what they saw was sufficient to cause them intense disquiet.

As in the earlier attack, the Blackfaces had used the waters of the lake as cover for their approach, and the bursting bomb had the same effect as formerly.

Leaving the water immediately the explosion took place, for a time they could be seen in the feeble rays of the spotlight flying hither and thither in apparent confusion.

Presently their disorder abated. They retired some distance from the scene of the explosion, and a council of war was held, resulting in the detachment of several small parties from the main body.

This movement was discovered by Ned, who discerned isolated parties flying across the path of the spotlight's beam.

In reply, Rogers' automatic spat lead. A Blackface suddenly arisen from the water had gained a footing on the rocks, only to crumple and fall back into the lake as the report of the shot awoke the echoes. A deafening crash on the left certified that Jim was not idle: he had dealt with three of the attackers by landing a bomb in their vicinity.

Scanning the water of the lake in front of their position, Ned saw that it looked troubled.

The bomb did its work and sent a dozen Blackfaces into the air. Then staccato crashes on the cavern wall at their backs warned them to beware of the flying clubs.

The Blackfaces seemed to be fearless and, although unaccustomed to the effects of firearms and explosives, they continued to attack. Ned sprayed them with bullets from his Winchester, and an occasional splash told them that he had not missed.

Presently came a cry from Jim, telling them that he had been hurt. Quickly turning the spotlight to where Jim was, Ned saw the blood streaming from an ugly wound in his cheek—saw, too, that he was trying to light the fuse of a bomb, and that almost within reach of him a Blackface was preparing to spring upon his chum. Rogers also saw Jim's danger. With a Blackface club in his hand, he leapt the breastwork. As he landed he felt himself clasped by a claw-like hand. With superhuman effort Rogers tore himself free and, side-stepping the less agile Blackface, swung his club and struck. Toppling backwards, his opponent lay inert, but still alive.

Not caring how his opponent had fared, Rogers made for Jim's attacker. Engrossed with his designs, the Blackface did not become aware of Rogers' proximity until he was nearly within striking distance. The Blackface also carried a club. With lightning alacrity he drove at Rogers' legs, missing only by a hair's breadth. Before he could recover, Rogers, as if making a stroke at golf, brought the club down on the spiked skull of the Blackface.

As Rogers leapt the breastwork to go to Jim's assistance, the attackers gained footing on the rocks. Now they were beset on all sides. Ned's Winchester was temporarily useless, its magazine empty. He watched Rogers gain a rock and, surrounded by menacing Blackfaces, use his club like a flail.

To use a bomb was out of the question, for he might injure Rogers. But Ned's automatic was still full, and, aiming carefully, he fired at a Blackface who, with raised club, was taking Rogers in the rear.

"One," said Ned between his teeth, and "Two," as the second shot rang out and another Blackface sagged on the rocks.

Suddenly Ned turned sick with dismay. Rogers was down. Yet before Ned could sight his automatic again another combatant had engaged the Blackfaces. Jim leaped in among them. The suddenness and ferocity of his attack momentarily beat back the jubilant Blackfaces.

The opportune intervention enabled Rogers to regain his feet, and back to back the man and the boy fought. Only one more shell remained in Ned's automatic, and Rogers' warning flashed through his mind. Should he reserve it for himself?

"No!" he said, almost aloud, and "Take that," he gritted, as he fired his last shot with deadly effect. Then, club in hand, Ned joined in the unequal fray.

With superhuman valour they fought, but gradually they were forced toward the breastwork, until with a concerted rush they drove the Blackfaces back.

In obedience to the command, the boys leapt the breastwork, while Rogers, with a whirlwind rush, pressed the attackers back and covered the boys' retreat. Again the tide of battle turned. Finding himself compelled to retreat, Rogers suddenly turned and vaulted the breastwork.

As Rogers gained cover, the boys, with deadly precision, hurled dynamite bombs into the midst of the enemy. Then, bomb following bomb, gradually drove back the attackers, who were now massed on the rock in front of the breastwork.

The bombs had caused great havoc in the ranks of the Blackfaces, but pressure from behind sent them forward again with a surge. On they came in an overwhelming rush. Again missiles began to crash against the cavern wall. Apparently nothing could withstand them.

Attacking also from the air, the Blackfaces were making victory a certainty. Desperately pressed, the explorers were exhausted with their efforts to stem the tide of battle. Standing shoulder to shoulder, each held a bomb—their last.

Steadily nearer the Blackfaces came. The critical moment had come. Three matches rasped, simultaneously touching the powder, and three fuses spluttered as one.

With fuses alight and six seconds between them and oblivion, three desperate men awaited the end.

The seconds flew by, yet every second was an aeon. Each uttered a short prayer, which in Rogers' case changed to a command.

"Throw!" he called abruptly, and the hissing bombs hurtled on their mission of destruction.

In those three fateful seconds Rogers had seen something that raised a hope in his breast that they might yet win out. His keenly searching eyes had seen the advance guard of the Birdman army. With a mighty rush they came swooping down upon the exposed Blackfaces. Every Birdman picked his mark for his deadly club.

Before that onrush the Blackface army crumpled. Still the Birdmen came. Squadron after squadron took toll, until the rocks were strewn with dying Blackfaces, while those who had taken wing were pursued relentlessly by the Birdmen.

When the turmoil of battle had abated, the explorers' first thought was for the safety of their boat. Quickly making their way to where it had been moored, they were relieved to find it floating safely in the natural miniature dock where it had been hidden. Luckily, it had escaped the notice of the Blackfaces.

Returning to the scene of the fight, they saw the Birdman advancing towards them. At their approach he quickened his steps and showed evident delight. To their astonishment he had become articulate. In a low musical voice he uttered some words, which, although unintelligible to his listeners, yet conveyed to them a greeting. Advancing, Rogers placed his hands on the Birdman's shoulders. The Birdman returned the caress. Ned and Jim followed Rogers' cue and the Birdman responded in the same manner. A bond of brotherhood had been cemented between them.

Fortunately, the defenders of the camp had suffered no serious injury. Jim's wound caused by the handle of a flying club was dressed by Rogers. Ned and Rogers had escaped lightly; bruises and bleeding knuckles made up the sum total of their injuries.

The advent of the Birdmen at the crucial moment had saved them. Ned and Jim had entered the fray as light-hearted boys. They emerged with the seal of manhood upon them. There was a graver look on their faces and an expression of deeper thought in their eyes as they contemplated the result of the conflict.

Flushed with victory, the pursuing force had returned, until many hundreds of Whiteface Birdmen were grouped in military formation awaiting orders from their leader, who was none other than the lone Birdman of the caverns. Presently the expected order came. The groups broke up as each Birdman sought a convenient resting place. Then bags, like small haversacks, containing food were produced. Having eaten, in obedience to another order, the Birdmen set to work to collect the fallen. The lake was systematically searched for bodies.

Fastened together by means of light chains produced from the bags, all the bodies were taken in tow by Birdmen, who swam steadily westward. Not a Blackface remained alive. The wounded Birdmen were carefully tended.

Rogers, Ned and Jim watched the weird performance with questioning eyes. Noticing their perplexity the Birdman conducted them to where the camp fire smouldered. Pointing to the fire, he then indicated the bodies of friend and foe, and enlightenment came. The corpses were being taken away to be cremated. Obviously here in the bowels of the earth dwelled a race more advanced in one respect than some of the civilized peoples of the outside world.

"Sanitation necessarily is a strong point with these Birdmen," Rogers commented. "They could not live in these caverns without a rigid observance of its laws. The waters of the lakes must be kept undefiled or the Birdmen would perish."

When the fatigue party was out of sight, the Birdman motioned them to follow. In a few minutes everything was ready, and they entered their boat, thankful that they were leaving a spot where Death, in passing, had brushed them with his wings.

The main body of Birdmen remained to act as rear-guard. Unexpectedly meeting with such a determined resistance, which had culminated in their own defeat, the Blackfaces would certainly return to give decisive battle.

CHAPTER XVII. — THE DEATH PIT

AS the three wanderers followed in the wake of the swimmers, they felt no elation at the result of the conflict which had been forced upon them. A feeling of thankfulness for their providential escape was tempered by regret for the necessity which had compelled them to use their weapons against the Blackfaces.

The procession ahead was a gruesome reminder of the fight. Among the slain were many of their Birdman's friends. It seemed strange that even these caverns were not free from the evil of war. Their advent had not been the cause of the conflict, which was possibly but one of many fought over the centuries. That the Blackfaces were on an expedition of aggression against the Birdmen was apparent, and the white rovers' entry into the conflict was purely accidental. It was possible that they might yet be further involved in the dissensions between the two parties. In such an event they must help their friends the Birdmen to the fullest extent.

These unspoken thoughts occupied their minds during the greater portion of the journey. The Birdman occasionally appeared out of the darkness and, for a while, accompanied the boat as if to assure himself of their safety.

It was during one of these visits that he directed their attention to a change of direction. They were leaving the broad waters of the lake and entered a narrow passage which trended in a southerly direction.

For a time they followed the new course. Then the passage opened into another lake, the smallest they had yet met with. They had, it seemed, reached their destination, for, nearing the far side, they found the lake shore already tenanted. Figures, seen on the rocks, seemed to be awaiting their coming.

As they entered upon this inner lake, a marked increase above the normal temperature of the caverns was noted. Jim first remarked upon the change.

"This is as hot as a Turkish bath," he complained. "I wonder if the water is warm also," and he plunged his hand into the water experimentally.

Presently they found that the rocks on which they landed were also warm, the reason for which they were soon to learn.

Led by the Birdman, they followed a well-worn path which led upward until they came to a cone-shaped rock with a natural parapet on the top. Looking over the parapet, they gazed down into a chasm of great depth, at whose bottom something glowed faintly red. Unwinking, it seemed to look up at them balefully through the darkness of the pit, like an eye of some monster of the infernal regions. From the chasm fierce heat emanated, and the rocks on which they stood and the parapet over which they leaned were hot to the touch.

This, then, was the place where the Birdmen disposed of their dead. While they gazed spellbound, the cortège bearing the bodies arrived at the top of the cone. Without delay, the Birdmen proceeded to carry out the last rites to friend and foe.

In the centre, a portion of the parapet had been cut away, and the rock bevelled to form a chute. Preliminarily, the bodies were placed upon a rock dais at the top, and one by one passed onward to the chute, which spilled them into the furnace below.

At the conclusion of the ceremony the spectators were turning away when their attention was arrested by the approach of a party of Birdmen. In their midst, with arms and wings pinioned, was a Birdman prisoner. Expressionless of feature, he walked onward with firm steps.

By the parapet, the fettered Birdman was placed in a prone position upon the funeral dais. Understanding of the situation came to the three onlookers. The Birdman was to be executed— cast, living, into the fire below!

A few words were addressed to the prisoner, who replied briefly, and simultaneously shook his head emphatically, obviously in denial of some charge made against him.

To Rogers conviction came that a miscarriage of justice was about to take place. He had seen the motion of denial made by the condemned Birdman and became unaccountably impressed by the sincerity of the action. Should he interfere, he wondered. He would at least try to save the condemned Birdman.

Stepping quietly to the platform, he placed a hand upon the fetters which bound the recumbent Birdman. To the surprise of the boys, the guard stepped gravely back. Turning, Rogers beckoned their friendly Birdman, who at once approached. Pointing towards the furnace, Rogers again placed his hand upon the prisoner. Looking straight into the leader's eyes, he shook his head.

Rogers' intimation was immediately understood. Turning to his followers, the Birdman spoke rapidly. With apparent deference they listened, and when he concluded a murmur of approval arose. At a command, the prisoner was lifted from the rock and placed upon his feet, and his fetters were removed. Open-eyed, the boys watched.

Again the Birdman spoke, and the reprieved creature advanced to where Rogers stood, and sinking down before him, with his forehead touched the rock at Rogers' feet.

Now the Birdman chief motioned from Rogers to the crouching figure. Rogers understood. The creature whom he had saved from the furnace of death belonged to him.

Leaving the pit of death, the trio returned the way they had come. As they emerged from the passage into the lake, another surprising incident claimed their attention. Passing to the eastward, several rafts, pointed at stem and stern like a double- ended boat, were propelled by Birdmen using short paddles. Closer inspection showed the rafts to be loaded with provisions and implements of war, including a goodly number of iron clubs.

These supplies were intended for the army of Birdmen who were defending the western passage against the marauding Blackface army. Provision was being made to withstand a determined attack on a large scale. It was possible that an attempt would be made by the Blackfaces to push their attack even to the home of the Birdmen. That every available defender was required was demonstrated by the fact that all the Birdmen who took part in the disposal of the fallen flew hurriedly eastward upon emerging from the passage.

The Birdman did not join the reinforcements, but, with the late captive rescued by Rogers, accompanied the boat westward. By signs he indicated that speed was necessary, and to attain that object he resorted to an expedient which proved that he was capable of adopting methods to suit the situation.

The mooring line lay coiled in the bow of the boat. It was of goodly length, some ten or twelve fathoms. Seizing it with his toes, he rose in the air and flew slowly until the line was tautened by the resistance of the boat. To aid him, Rogers and Ned, who were paddling, redoubled their strokes, and the boat sped through the water with increased impetus. Once well under way, the Birdman did not seem to have any difficulty in keeping it moving, but, as Jim watched, the thought came to him that as they had plenty of line, the services of the second Birdman might be utilized to assist his companion. Moving forward, he affixed the second line to the bow cleat, then signalled to Rogers' Birdman, who was swimming alongside, to follow the example of his leader. Jim passed him the line and he immediately rose.

"Good team work, Jim," grinned Ned, as the second willing helper took to the air. The additional power now caused the boat to travel so quickly that the paddles became unnecessary. Then Jim voiced a fear.

But the boat went on steadily, and Jim's fears of disaster became overshadowed by admiration for the endurance shown by the Birdmen in drawing a heavily-laden boat at such a speed without apparent effort.

Thus they sped for a time, when they suddenly became aware that they had picked up an additional escort, for behind them and on either side flew a squadron of Birdmen.

Their two friends now returned to the boat, having handed the lines over to a relief. Ahead dull red lights at intervals burst into brilliant flame.

The wanderers now realized that one eventful stage of their journey into the unknown had nearly ended. What would they see or find? Fate had led them to the haunts of the strangest creatures the eyes of man had ever seen, to find, perhaps, something stranger still—something even more incredible than that which they had experienced.

As the boat drew nearer to the lights, its occupants saw that the illumination was produced by a number of fires built upon natural shelves of flat rock extending across the full width of the lake. Sentinels were revealed; some were standing, but others crouched on the rocks. Alternate fireless plateaus were tenanted by Birdmen guardians of the inner waters.

Passing through this first outpost of the Birdmen's home defences, more lights were seen flickering in the distance. After passing the barrier the Birdmen increased their speed. Relay after relay had taken their turn in towing the boat, and now the wanderers felt that they had at last arrived at the portals of the Birdman city.

When nearing the shore, the explorers became dubious about finding a suitable landing, for the rocky shore rose steeply from the lake. Presently, however, the Birdmen swerved to the right and flew parallel with the shore until a crack in the cliff disclosed a tiny harbour whose shore sloped gently to the water's edge. Their self-imposed task completed, the Birdmen dropped the towing lines and the boat floated gently in to the landing.

CHAPTER XVIII. — A MYSTERY SOLVED

GLAD of the opportunity, the boys landed. The boat was unloaded and then lifted out of the water. This done, the Birdman chief issued an order. The gear was apportioned among his subordinates and at a signal they moved up the sloping rock, followed by the chief with Rogers, Ned and Jim by his side.

They traversed a well-worn path thronged on both sides by the strange creatures of the caverns, who, as the procession passed, sank to the ground in homage to the three white strangers from the outside world. At the top of the slope the way lay level, until the cavern wall seemingly would bar their progress. As they drew nearer, an aperture opened, where sentinels were on guard. The adventurers were at the gateway of the Birdman city.

Rapidly passing through these portals, they found themselves in a vast cavern high above the level of the lake, and the habitations of this strange race became visible.

Grottos honeycombing the cavern walls apparently served the Bird-people as dwellings.

As the three strangers proceeded the crowd became denser. On both sides, as far as their limited vision allowed, the weird figures of the Birdmen thronged, and as the cortège proceeded, the concourse bowed in homage to the ground, producing the effect of an animated, onward-rolling, sluggish wave.

At length the carriers halted, and drew aside to allow the Birdman chief with his three charges to pass.

They were now at the farther side of the cavern at a place where a level rock at shoulder height jutted from the cavern wall. A flight of steps led to the top, and, facing the steps, a carved rock shaped like a chair, with a high recessed back, occupied a commanding position and conveyed the impression of a throne. Behind it an arched aperture in the cavern wall loomed darkly.

Reaching the steps, the Birdman in charge motioned the three explorers to remain. Ascending the steps, he passed behind the throne and entered the arched opening. A few moments later a light was observed, which grew brighter as the moments passed until the archway became brightly illuminated.

Now the light moved forward. From behind the throne a group of torch-bearers appeared. Passing half each side of the throne, they joined up in two segments of circles from the throne and the steps. When the torchmen were in position the Birdman chief appeared. Facing the throne, he raised both hands above his head and all the Birdmen followed his example. Kneeling, he touched the ground with his forehead and arose. These actions of devotion were imitated by the multitude.

Rogers and the boys, standing by the bottom step, were completely mystified. Speculation as to what was about to happen was uppermost in their minds. Again the Birdman chief raised his hands above his head. As he did so the back of the throne moved aside and revealed a figure flooded by the torchlight.

By Rogers' side his two boy companions stood with staring eyes. Through lips hardly able to frame the words came in an awed whisper—"A white girl!"

Level with the seat of the throne, with arms upraised as if invoking a blessing upon the multitude crouched at her feet, lithe and graceful of body, bare-armed and bare-footed, stood a girl. Despite the remnants of a one-time dainty frock, her poise was that of a young goddess. A mass of dark hair falling below her waist made a background to a face seemingly chiselled out of marble, so pallid and transparent was it. Her dark eyes, in contrast with the pallor of her cheeks, assumed heightened brilliance.

Perfectly at ease she stood, the light from the torches playing on a wondrous string of pearls which graced her snow- white neck and bosom. Pausing in benediction a moment, the girl let her hands come slowly to her side, and with regal grace seated herself on the throne to the accompaniment of a chant whose cadences were seemingly in harmony with the weird surroundings, rising and falling like the sigh of a fitful wind. Abruptly the chant ceased, and the echoes began to play their part. Sounding faintly in the distance and gradually swelling until they filled the cavern, to pass away in decreasing volume.

While the echoes sounded the Birdmen remained motionless. Complete silence reigned. When the last whisper had died the ceremony was resumed.

The three cave-explorers stood with eyes riveted upon the girlish figure on the throne. Apparently she had neither seen them nor been informed of their presence. If she had seen them at the bottom of the steps without betraying the fact, the girl's self-control was incredible. Sitting statuesquely, with hands resting lightly on the edge of the seat, she betrayed no knowledge of their presence. But under that tranquil exterior a girlish heart throbbed wildly, and expression of the pent-up emotions of three long and terribly lonely years was with difficulty repressed.

During the ceremony three years of hopelessness passed in rapid review. Suddenly torn from the glorious sunshine of the outer world to awaken in the bowels of the earth, she had found herself tended by strange, winged creatures, denizens of a region of eternal night. Without hope of succour, she was doomed to remain in that awful place—perhaps never to see a human face again—and, magically, at the bottom of those steps, stood three human beings! Two boys and a man of middle age. There was something vaguely familiar about the poise of the older man. It reminded the girl of someone she dearly loved. But it could not be.

Now the faces of the boys claimed her attention. Were they real or visions conjured out of the darkness? No, it was no hallucination. They were moving towards her up the steps: one, two, three; they had reached the top. Eight steps; she had counted them. Still she did not move. They advanced towards the throne. Fiery hammers began to beat in her brain. They were closer, the older man a pace ahead of the boys. Smiling, with outstretched arms, he advanced towards her. He was speaking— calling her name.

With a quivering cry, she rose to her feet. Her doubts were ended. He was real. The boys at his side were flesh and blood. They, her old playmates, Ned and Jim, also were calling to her. She heard them faintly as if they were far off. Two strong hands were meeting hers. With a sigh of infinite content, her head pillowed on Rogers' breast. His grave blue eyes looked down upon her. She heard an old familiar voice, quivering with suppressed emotion, say fervently:

To Rogers and the two boys standing at the foot of the steps, waiting, the appearance of a white girl at the back of the throne came as an amazing climax. That a young girl could find her way into the caverns had seemed unbelievable. What trick of fate had brought her there? Rogers' analytical mind was trying to solve the riddle even as she took her seat on the throne. He noted she was clad in a modern costume, but it was shorter by inches than that usually worn by a girl of her age, which he judged to be about eighteen years. On a girl of fifteen it would probably be the correct size. Three years between fifteen and eighteen— possibly that was the length of time she had been in the caverns.

Rogers cast his mind back over the past three years and called to mind the most notable incidents which had taken place during that period. "Three years ago," he mused, and the events of that year passed rapidly in review. Subconsciously he found himself reading a telegram marked "Urgent," which he had received one morning at his office. The post town was Blaircourt. It was addressed to Major J. Rogers. It read:

The mental reading of this three-year-old telegram caused Rogers to start. Could it possibly be Judith, the only daughter of his sister Marion, who disappeared untraceably from Blaircourt Station? Rogers looked more closely at the figure seated on the throne and his heart-strings tautened. Yes, it was Judith, whom he had dangled when a baby on his knee—with whom he had romped in later years. Judith, the playmate of Mel, Ned and Jim. Realization that the bonny girl, who had been mourned as dead, was seated before him, caused Rogers to exert all his power of self-command to prevent him ascending the steps and taking the girl in his arms. Surely never before had Fate planned such a remarkable reunion.

Judith Blaircourt lived. By strange and devious ways, they had been brought to her—perhaps to share with her the horror of life-long imprisonment in these dread caverns of eternal night.

Rogers' meditations were interrupted by the cessation of the chant, whose last echoes were fading away. The Birdman chief gave the signal for the strangers to ascend the steps to the throne. As they moved upwards, Rogers, in a low voice, warned Ned and Jim of the amazing meeting.

"Hold yourselves well in hand," he said. "The girl seated on the throne is your old playmate, Judith Blaircourt."

At mention of Judith's name, one of the boys felt as if the world was tumbling about his ears. With his soul in his eyes, he gazed at the girl enthroned above him. Judith, his boyhood sweetheart, alive, and he was about to meet her! Would she remember? Half-believing, half in doubt, Ned mounted the steps. A few moments later he was awakened from a maze of conflicting hopes and fears.

"Ned, and you, Jim, too, have come to me," a gentle, well- remembered voice broke the spell.

CHAPTER XIX. — JUDITH BLAIRCOURT'S STORY

WITH stolid face devoid of expression, the Birdman Chief observed the meeting between the Bird-people's queen and the three white men. Meeting his eye, Judith addressed him in a low voice. Presently the Birdman turned towards his waiting people. Raising his hands for attention, he spoke. When he had finished, the assembled Birdmen saluted by raising their hands. Then they dispersed quietly. Only the torch-bearers remained.

"I commanded him to dismiss the Birdmen, who have made me their queen," explained Judith. "I hold the power of life or death over them all—even over the Birdman chief, who is the executive ruler. My slightest wish is obeyed. Needless to say, I rule this strange race by tempering justice with mercy."

The Birdman chief now returned and, by Judith's command, they were escorted from the throne to the archway. Preceded by the torch-bearers, they entered a circular chamber in whose walls many openings or doors could be discerned. At the centre door the Birdman, after prostrating himself before Judith, withdrew by the way he had come, and they entered the chamber sacred to the queen.

Alone with her friends, Judith cast off all queenly dignity. Throwing her arms about Rogers' neck, she kissed him on both cheeks. Ned and Jim were welcomed in the same fashion, and Ned returned Judith's salutation with interest.

They were playmates again. The chamber, illuminated by a single torch, became transformed into the sunny slopes of "Blaircourt." Judith was happy. Three years of darkness was being compensated for by the sunshine their presence brought. Companionship with her own kind! It was wonderful—unbelievable— yet true.

Seating herself on a carved stone, Judith struck a piece of metal rod suspended from a frame. A silvery tinkle resulted, and through an adjoining opening attendants entered, bearing metal trays upon which were platters of food and metal bowls containing water. The refreshments consisted of fish garnished with fungi of the mushroom variety, which Judith assured them was a delicacy and one of the staple foods of the Birdmen.

"By the way, Judith, how would you like a stick of chocolate?" Ned asked gravely.

"I would like it first-rate, my good Ned." Judith laughed, deciding to fall in with the jest. "But it is after shopping hours and you can't buy anything down here after dark."

"That is so, Judith," Ned returned, pleased at Judith's quick wit. "But there is no underground law to prevent a store-keeper broaching his own stock."

"I suggest, Chief, that our belongings, including the boat, be brought to the chamber outside," Ned said to Rogers. "It will leave them handy in case of emergency."

"A good suggestion," agreed Rogers. "Can we have our belongings brought here, Judith?"

Judith again struck the metal rod. Instantly, attendants appeared to whom Judith gave instructions.

"Everything will be here in five minutes," she announced, "including, I hope," she added mischievously, "Ned's milky chocolate."

A few minutes later Ned had vindicated his reputation for veracity, and Judith and the milky chocolate had become acquainted.

"There are probably other things amongst our kit, Judith, which may be of personal use to you," suggested Rogers. "Handkerchiefs and what-not. You can go through our pack and appropriate what you require."

"Handkerchiefs, Uncle Jack!" breathed Judith. "I only had one when I arrived here, and I wore it out the first week crying into it."

"Everything is yours and ours, Judith. Henceforth we will, not figuratively speaking, but actually, be all in the same boat," Rogers said. "If you feel in communicative mood, we are wild to hear your story."

"Certainly, Uncle; I am too excited to sleep," Judith said. Seating herself on a low rock, she commenced:

"Three years ago at vacation time we were a merry party at Blaircourt. Ned and Jim were there, I remember. Mel had brought some of her school friends—and the house," she criticized reminiscently, "was like bedlam. Heavy rain had fallen for days, and we had to keep indoors. The lake had filled to many feet above its flood level, and we had been warned not to venture out upon it. I remember when we were very young, Mammy, our old black lubra nurse, telling us about a debbil-debbil which lived in the lake.

"'You children go in lake,' she warned, 'debbil-debbil come and swallow you up. Long time ago, black fella man, big fella king, he go on lake in canoe, big flood-time. Debbil-debbil he come, drink up lot water, swallow black fella king, swallow canoe, all gone, not come back again.'

"Child-like, we looked upon Mammy's story as an old aborigine fairy-tale or legend, and forgot her warning."

As Rogers listened to Judith, his thoughts wandered to old Bal-yari's token. The debbil-debbil of the lake at Blaircourt had swallowed up the black fella king and his canoe, and he never came back again. Light dawned on Rogers. The black fella king was the carver of the token. A chance story told to children by an old lubra had unravelled a mystery, centuries old. The old aborigine legend of the debbil-debbil of Blaircourt lake was founded on fact, for Rogers now knew that it was the debbil- debbil who swallowed Judith Blaircourt.

"Suddenly the rain ceased," continued Judith, "and one morning the sun shone in a cloudless sky.

"It had been decided overnight if the weather broke, to hold a picnic some miles away from Blaircourt. At the last moment I found I could not join the picnic party as mother was down with one of her periodical attacks of headache. The party set off full of good spirits and I was left to tend mother. By midday her headache had disappeared, and, as I had nothing to do but read, I thought I might as well go for a row on the lake and take a book along with me.

"Without telling mother of my intentions, I wandered off to the lake, launched a skiff from the boat-shed over whose floor the flood water was just lapping. Rowing well out into the lake, I laid in the sculls and allowed the boat to drift. Making myself comfortable in the stern with cushions, I commenced to read. How long I read I do not know, for I must have fallen asleep. I was awakened by a violent movement of the boat and found I was on the outer edge of a great whirlpool. In desperation I seized the sculls, but they were soon torn out of my hands. The boat went spinning down into the vortex. Then the water closed over me and I remembered no more until I woke in these caverns. I had been carried down on a great flood which I afterwards learned, ceased abruptly. The debbil-debbil had got me, as it had got the black fella king of Mammy's story.

"What happened, Uncle Jack, when it was found that I had disappeared?" Judith asked.

"Everybody was at a loss to explain it," replied Rogers; "nobody had seen you on the lake. A boat was certainly missing and the lake had fallen unaccountably, but there was nothing to connect your disappearance with those incidents. If the lake had continued to fall, we would have suspected something unusual was happening, but after the first breakaway of the lake bottom debris must have filled the cavity, which, once more becoming watertight, removed the condition which caused the whirlpool. Search parties roamed the bush with the hope of finding some trace of you, and the lake was dragged. After weeks of searching, further efforts seemed hopeless, and you were looked upon as dead."

"When I awakened," Judith resumed, "I found myself lying upon a flat rock just where the throne now stands. Around me were grouped a number of the strange creatures of the caverns, but they do not seem so strange to me now. Some were holding torches and when I saw that they had wings, all the bad things I had done came back to me for I thought that I was about to be punished for my sins. It was terrifying, but I gradually realized that they were not there to harm me. They forced morsels of cooked fish between my lips and some cooked fungi, letting me sip small quantities of water at intervals.

"Soon I became stronger; then the full realization of the terrible position I was in came to me. I was entombed alive in the bowels of the earth amidst a strange race of winged creatures. The shock of my discovery nearly unhinged my mind, but the creatures of these caverns are wonderfully sympathetic and their understanding of a helpless creature's physical needs is superior to anything I have known among human beings. Patient, inoffensive, self-sacrificing, they live for one another and I, a stranger from another world than theirs, aroused their pity and later their homage, for during the three years I have been here I have used the limited knowledge I possessed to assist them to attain a greater measure of comfort than they had before I came among them. They have repaid me, for they have made me their queen.

"Theirs is a community life. There is no barter or exchange. Everything belongs to the commonwealth. They are a cleanly race. The drainage from this city flows south far away from the lakes. Offal is burnt in the pits in which eternal fires burn in parts of these caverns. There are hot springs and lakes and mineral waters in abundance. The lakes are depended upon for the supply of fish. They have learnt from necessity the art of the fish hatching, otherwise the lakes could not provide the population of the caverns with sufficient food.

"They are a contented race, yet even down here a state of almost continual warfare exists. Between these lakes and the debbil-debbil lake at Blaircourt, there is another race of Birdmen—the Blackfaces—who are cannibals. They are indigent and live by preying on the Whiteface Birdmen; but their numbers are gradually dwindling and it will not be long before they are extinct. Even now they are raiding our lake territory and a strong force has been sent against them. I had heard of your coming, for your friend, the Birdman chief, who escorted you to the throne, told me of your presence in the caverns.

"'Three strangers of my own race were journeying westward,' he said. The return of this chief of the Birdmen caused great rejoicing, for he had been sent out alone to the most distant parts of the lake without food, fire, or other means of sustenance, where he must remain for a stated period. He was not to speak during his probation. If he performed his duty conscientiously and returned at the stated time, he would then be considered a fit ruler, for he is virtually king.

"He related how the white strangers had succoured him in his extremity, and how they fought the Blackfaces. It was at his request that help was sent to you, for which I thank God, for you have reached me safe and sound. You need have no fear of our Birdmen. Place implicit trust in them; they will trust you likewise.

"The Birdmen do not glory in or tell of heroic deeds. What in our world would be called heroism, is to this race merely duty. They will willingly die for the good of the community and the dead are not mourned. Law-breakers are invariably punished by death, but punishment is very seldom necessary. They have a moral code of the strictest nature. Partners are selected from groups far removed from blood relationship and the physically unfit are practically unknown."

Judith's audience listened with admiration to the easy flow of her talk. The years of her confinement in the caverns had not dulled her intellect. She had accepted the altered conditions of her life without flinching. With mind pure and unsullied she met the problems confronting her and had emerged from her ordeal possessed of a philosophy which gave her strength illimitable to meet whatever trials the future had in store.

While speaking Judith's fingers strayed to the pearls upon her bosom. Cupping her hands, she held the precious things for inspection.

"Are they not wonderful?" she asked. "I do not wear them merely for personal adornment, but because of their exquisite beauty. Like all rare gems, they have been obtained at the cost of life. They were wrested from the very jaws of their guardian. Originally they came from a distant cavern beyond the waters of the Blackfaces' domain where an ancient mussel bed, uplifted from the ocean countless years ago, exists.

"These pearls were brought back by the survivors of a party of Whiteface Birdmen who penetrated through the Blackface waters at great hazard, to find their way barred at last by the terrible monster that guarded the treasure. The Birdmen were not interested in the pearls. They meant nothing to them, as gold also means nothing, for there is gold in abundance in many parts of these caverns. There is more of the yellow metal here than the world has ever seen.

"Look!" Judith held up a platter. "That is of solid gold which I have beaten out with my own hands. It comes from a place of absolute darkness, where no luminous rocks pierce the gloom. So it is found, as is other metals, by the light of torches. Although the Birdmen have the faculty of perfect vision in the semi-dark, as I have acquired, they are at a loss when they wander beyond the belt of luminous rock, and therefore provide themselves with artificial light.

"Having reached the cave of pearls, they collected the largest as a record of their adventure. When about to return, their way was barred by a gigantic serpent which lay across the entrance to the cavern and effectually cut off their retreat. The entrance was too low to enable them to fly to safety, so they decided to attack the monster with stones. Their blows only lashed the monster to fury. One Birdman attempted to leap across the obstructing folds of the serpent, but in an instant was enveloped and crushed to death. Becoming desperate, they made a concerted rush. Four were crushed in the serpent's constricting coils, and two only escaped.

"These are the pearls they brought back. This happened long ago, but neither Whiteface nor Blackface Birdman has since attempted to pass the guardian of the pearls. Sometimes the serpent leaves its haunts and journeys down the lakes. When it is seen, consternation reigns throughout the caverns, for it attacks every unwary Birdman who happens to cross its path. The guardian of the pearls is a menace even greater than the raiding bands of Blackfaces, for it appears where least expected. It moves with incredible speed and, from Birdmen accounts, is a most formidable antagonist to meet." Judith paused, then continued her story of the Birdmen.

"Music has a strange fascination for them," she resumed. "They delight in holding sing-songs. You have heard them chant; that was in my honour. I sometimes sing to them and they are very patient listeners."

"Lucky beggars," muttered Ned. He remembered Judith's glorious voice of three years ago. "What it must be now?" he mentally questioned.

"Judith," said Rogers, "we can provide them with a musical programme, for we have brought with us a radio outfit, both for transmission and reception, with which we have kept in touch with our friends outside."

Judith's eyes glistened at the thought of once again hearing the voices of her loved ones. Rogers read her thoughts and said gently: "After you have heard our story we will leave you to decide whether we will tell them that we have found you. I will tell you now of the chain of events which have led us to the homes of the Birdmen and to you."

Judith listened eagerly to the strange story unfolded by Rogers. She heard of the closing of the means of exit, but made no comment, although a newly-cherished hope that they had come to deliver her had formed in her breast. She now knew that all chance of escape by way of the bush-rangers' cave had been cut off, for Rogers had told her that although the tunnellers had not directly communicated their fears, he knew they had practically abandoned all hope of ever reaching them.

Rogers briefly outlined their journey up to the time of reaching the cave of a thousand columns. Judith surmised that the skeleton must be that of a previous prospective ruler of the Birdmen, sent out, as was customary, to qualify for the high position which awaited him if his quest succeeded. Failing, he would have left his bones at the foot of the column. The Birdman had told her of such a one who never returned to claim his kingship.

She listened with interest to the account of their first meeting with the Birdman and of the part he played in their rescue during the flood and of their subsequent encounter with the Blackfaces.

The narration of the means taken to beat off the attackers thrilled Judith. She said that the echoes from the exploding bombs had even reached the Birdman domain, and speculation had been rife as to what had caused such unusual sounds.

At the conclusion of the story of their journey, Rogers produced the token. Placing it in Judith's hand he said:

"This token was given to me by old Bal-yari. He told me that it would guide me through strange places, and, as he placed it in my hands, he added a warning 'BEWARE WHEN THE MOUNTAIN SHAKES.'

"You told us, Judith," Rogers continued, "of the old black lubra's warning not to go near the lake. The token was carved by someone having an intimate knowledge of the caverns. Probably by the black king fellow of the old lubra's story, who was swallowed by the debbil-debbil at Blaircourt.

"In addition to the token, this little box containing a pearl and a clay model of a serpent is proof that he passed through the cave of pearls. The Birdman may have some record of a stranger appearing among them. Have you heard of such a one, Judith?"

"Yes," Judith affirmed, "they tell of a black stranger who appeared in the caverns long ago. He lived among them for a time, then a great flood came and he disappeared."

"That seems to explain satisfactorily the origin of Bal-yari's token," confirmed Rogers. "The black king fellow evidently won his way through the caverns and found an exit through the cave in the old crater."

"You have heard our story, Judith," resumed Rogers. "You now realize that we, too, are prisoners, but still hope to find a way out." He looked at her inquiringly. Judith understood.

"We will not tell them that you have found me," she said bravely. "It would be cruel to revive hope in their hearts and then, perhaps, have to tell them the worst."

As Judith ceased speaking a messenger was announced, who proved to be the Birdman whom Rogers had rescued.

Translating his message, Judith informed them that the Blackface attack had reached a serious stage. The attackers had been heavily reinforced, and every available defender had been called upon in the endeavour to repel the invaders, who were slowly gaining ground.

This was serious news. A victory by the Blackfaces would be the end of their hopes of ever escaping from the caverns. They must throw their weight into the battle and perhaps they might be able to turn the scale in favour of the Whitefaces. Rogers voiced the thoughts which passed through the minds of the other three.

"We must decide upon a line of action, for we cannot enter into the fight without a concerted plan," he said.

Turning to Judith he asked: "Is it possible for some of the leaders to be brought here—the chief preferably? Whatever plans we make must have their approval and co-operation." Judith assented and spoke to the messenger who departed on his errand.

"They will come," she said. "In the meantime, I will tell you something of the fighting methods of the Blackfaces.

"Since I have been here there have been several attacks made, but never in such force as the present one. The Blackfaces seem to be desperate and are making a final effort to possess themselves of the food supply. They attack by air and water simultaneously. The air squadrons are formed of companies flying in wedge-shaped formations. The main body also mass in the same manner. The under-water fighting is deadly and silent. I have seen the after-math—the lake's surface strewn with the maimed and dead of both sides. There is no giving in when once two opponents get locked in a struggle. It is always to the death." Judith shuddered at the recollection.

"In the air they manoeuvre for position, then hurl themselves at their enemy as living projectiles; their heads sink between their shoulders, having only the spike on top visible, they aim at any vulnerable part of the body. A blow on the head will never kill a Birdman. If you happen to get into close quarters with one of them, strike at a wing, the lower part of the body or face, for the horny covering on the head is so hard that it would turn a bullet."

CHAPTER XX. — THE BLACKFACES GIVE BATTLE

JUDITH spoke rapidly, yet while she was speaking Rogers evolved a tentative plan of action.

"We will make the islands our first line of defence," he announced. "There we have an ideal base from which to operate. Our best chance of achieving success will be to take the Blackfaces by surprise. When they attack, let the Birdmen gradually fall back before them and concentrate at the islands, then if they approach within range, we will see what rockets will do to bring the Blackfaces to a more reasonable frame of mind. If we meet their massed attack with a barrage of rockets, I anticipate they will be momentarily thrown into confusion. Bombs exploded at the same time will add to the effect. Our Birdmen must be ready to attack immediately in full force. All this must be explained to them," continued Rogers, "particularly the nature of our rockets. It is necessary that the Birdmen be informed beforehand what they are to expect, otherwise they may become demoralized at the critical moment."

The Birdmen now arrived and Judith acquainted them with Rogers' plan. After an animated discussion Judith explained that the Birdmen had agreed to it.

"We can depend upon them," she said, "to do their part. They will carry out instructions to the letter."

Half an hour later the party had embarked upon the rafts, which, in tow of the Birdmen, were making rapid headway towards the islands. They were well equipped with munitions, and the spotlight had not been forgotten, as it would prove a valuable aid in locating the position of their enemies.

As they progressed it became apparent that heavy fighting had been in progress. Swimmers frequently passed the rafts. They were the wounded whose bodily hurts prevented them from taking further part in the battle. They made slow progress, the stronger helping the weaker.

The sight of the wounded Birdmen was a grim reminder to Rogers of the Great War with its never-ending procession of stricken men toiling painfully to the rear.

Dim flares seen in the distance soon grew into large fires as the swiftly moving rafts drew nearer.

Their coming was awaited. It had been planned that three islands were to be occupied by the party, the centre one being allotted to Rogers and Judith, the others were to be occupied by Ned and Jim. This arrangement gave command over a wide front, the flanks being guarded by a force of Birdmen strong enough to repel flanking parties. Upon landing hurried preparations were made and soon all was in readiness to meet the expected attack.

The scene was strangely weird. Overhead the beating of wings sounded like the sighing of wind in a forest. The Birdmen were keeping a never-ending patrol; it seemed as if a great elliptical wheel was turning on a horizontal axis. Each unit of the great wheel kept its position for a definite number of revolutions. Then, their watch ending, they swooped down to one of the islands for a respite. As they broke from the wheel, another unit rose and filled its place. The units were composed of twenty-one fliers. They flew in triangular formation. At intervals a unit would detach itself and fly off into the darkness, the gap being instantly filled from the reserves on the islands. These were scouting units. When they returned they again joined the reserves, where they rested until their turn came again to take the air.

The Blackfaces were gathering at their rendezvous. Raiding parties had rejoined the main body, and for a time a lull in the fighting had taken place.

The Blackfaces' camp bore grim evidence of the cannibalistic traits of its inhabitants. Gruesome relics were scattered about their fires, and victims awaiting the pleasure of their captors lay huddled within sight of the evil ceremonies which were enacted wherever a group of the fiendish creatures congregated.

The scene was inexpressibly horrible. On the rocks stalked evil-looking figures. Many infested the waters of the lake, which appeared to revolt against the presence of their loathsome forms, for when they emerged from its depths it seemed as if they had been cast forth as being unclean.

Hidden in the recesses of the cavern roof, bat-like forms clinging to projecting rocks, slept with their heads between their shoulders, gorged to satiety with their noisome meal. Others, with evil eyes aglow, awaited the signal that would send them to battle.

They had not long to wait, for a hoarse cry suddenly roused them into activity. Instantly the cry was repeated, and the Blackface army began to move. Company by company they formed upon the rocks. Then with a whirr of wings they took the air. Their numbers seemed endless as they swept through the caverns on their mission of death, with fierce eyes rolling and their slavering fangs gleaming in the darkness.

The watchers on the islands had already made the best possible use of the time at their disposal to prepare for the coming attack. A raft was moored at each island with a Birdman crew in readiness in case of emergency.

After a period of anxious waiting, scouts returned with the information that the Blackface army was approaching. Their warning had hardly been given when the wheeling Birdmen above were seen to be falling back. Then the spotlight stabbed the darkness, revealing the oncoming Blackfaces. Simultaneously rockets shot hissing across the Blackface front. By their light it was seen that the leading ranks were about to enter the water; they had deflected their course downwards whilst the air fighters were passing overhead.

Such was the plan of attack, but rockets had not entered into the calculations of the Blackfaces. The hissing serpents of fire broke among them with startling reports, and the attackers found themselves amid a cascade of blinding stars. The effect upon them was as anticipated. They checked their flight, soaring upwards in a corkscrew turn with the front of their bodies exposed momentarily. Quicker than thought, the great wheel of the defenders which had been turning ceaselessly, broke. It dissolved into thousands of living projectiles which hurtled on with incredible speed. Each projectile sped with unerring accuracy to its objective—the breast of an enemy.

They struck with a sureness from which there was no escape. The deadly spike did its work swiftly. The impetus of the attack carried the striker and stricken into and through the ranks of the Blackfaces. The shrieks of the injured rose in a wail of anguish as they were carried swiftly downward, impaled upon the spikes, towards the lake's surface. Before reaching its level their victors, with a sudden opening of wings, stayed their flight and the victims were cast torn and bleeding into the lake.

The release of the rockets was followed by quickly thrown bombs, whose explosions added to the demoralization of the Blackface air force. Shattered by the sledge-hammer blow delivered by the defenders, they fell into confusion, which made them easy prey for the well-organized Whitefaces, who lost no time in driving home their counter attack.

In their panic many Blackfaces took to the water, but the Birdmen did not follow, contenting themselves with clearing the air before dealing with the enemy in the lake.

A plan had been arranged by which the forces attacking by water were to be lured into a trap in which bombs were to play an important part. The under-water force was to be allowed to approach within range, when a bomb attack would be made. Scouts were to signal when the opportune moment arrived; they were to rise suddenly from the water just in front of the approaching Blackfaces.

Tense moments followed for the four humans whose fate depended upon the efficacy of the bombs which they held ready in their hands while awaiting the signal. Judith stood by Rogers' side, a tense little figure as she waited, without a tremor, for the moment when she must light the fuse of the deadly bomb which she held. She had pleaded with Rogers to be allowed to do her part and, reluctantly, he had instructed her in its use. There was a glow of pride in his eyes as he watched her.

As if catapulted from the water, a score of Blackfaces rose along the front. The scratch of matches, followed by tiny flickers of light indicated the alertness of the watchers. A few seconds later, four geysers of water rose at as many different points, and before the waters had time to subside, others followed.

Bomb after bomb hurtled into the lake until it became a turbulent mass of agitated spume from which the Blackfaces rose in scores, to be struck down by the waiting Birdmen who hovered overhead.

Those who left the lake returned to its bosom maimed or dying. Those who remained were hunted until in desperation they, too, rose, only to share the fate of their companions.

The Blackface horde was in full flight. Demoralized, leaderless, they sought the safety which was denied them. Broken, they fled. But few escaped the vengeance of the Birdmen, who did not cease their work of destruction until the remnants of the Blackface army, fear lending speed to their wings, disappeared in the darkness of their own domain.

CHAPTER XXI. — TWO FIGHTS TO A FINISH

THE battle in the air had been sharp and decisive, but in the water isolated affrays were still taking place. Lynx-eyed Birdmen patrolled above the lake watching for Blackface stragglers, who of necessity must rise to the surface to breathe. The slightest disturbance in the lake brought a Birdman down from the heights like a plummet.

From his island Ned watched with anxious eyes the hunters and the hunted. He was so engrossed with the spectacle of a battle between one of the marauders and a Birdman, which was taking place a short distance away, that he failed to notice a Blackface emerge from the water behind the island. At the moment he was the sole occupant, the Birdmen escort in charge of the raft having joined in the pursuit.

Presently claw-like hands grasped the rock and without apparent effort their owner drew himself up. Gaining the top, he stealthily took cover beneath a projection which screened him from the prying eyes of the Birdmen above. Presently he arose and, assuming a crouching position, paused ready to spring.

Unconscious of the menace behind, Ned continued to watch the combat. It was a grim struggle, but the Birdman eventually triumphed, greatly to Ned's satisfaction. He was about to give voice to a cry of elation at the Birdmen's victory, when a sound caused him to turn. It was the rattle of a pebble dislodged by the Blackface, that caught his attention, but too late. The Blackface had made his spring. Before Ned could evade his onrush, he was seized in a crushing grip and carried backwards into the lake.

Although taken by surprise, Ned did not lose his presence of mind. Fortunately his arms were free. Instinctively he filled his lungs before striking the water. As they sank, Ned realized that it was the intention of the Blackface to drown him. He must lose no time in freeing himself from his clutch. Placing his hand upon his opponent's face, he drew up his knees, then gave a mighty heave. The suddenness of this manoeuvre surprised the Blackface, who, taken unawares, slackened his grip. Another vigorous effort broke the hold, and Ned, free for the moment, quickly rose to the surface. He had evaded his enemy for a time, but realized that his immunity would be short-lived.

Gulping in deep breaths, Ned made for the island, but the Blackface was not to be denied. Swimming like an otter he followed. Ned, hampered by his clothing, knew he could not escape. Instinctively he felt the claw-like hands were again about to grasp him. In desperation Ned turned, and drove his clenched fist into the evil face. This gave him another moment's respite, but Ned realized that the unequal contest could not last long. Again the Blackface came within striking distance, and once more Ned essayed to strike, but as he struck, the Blackface sank below the surface. Ned felt his blood chill; he was to be attacked from below and dragged down.

Ned had once fought a shark with his bare fists in an endeavour to save a comrade, but that occurred in the light of day. Here in the darkness, with this more subtle and no less ferocious enemy, he had not even a fighting chance.

As the Blackface sank from view Ned made one last desperate effort to reach the island. Swinging into a crawl, he made for the rocks. He had traversed a dozen yards when a disturbance in the water alongside told him his enemy was still close, but why, he wondered, had he not attacked from beneath?

Suddenly Ned realized that help had arrived. He saw his late antagonist engaged in a death struggle with one of the Birdmen. The fight did not last long. Soon a black body lay floating in the lake, and Ned found himself being swiftly towed towards the rocks where Birdmen helpers lifted him from the water. Succour had come just in time. When the Blackface sank to attack from below, a scouting Birdman had dropped from above and, as the Blackface was about to drag Ned down, he found himself face to face with another and more formidable opponent.

As Ned watched the floating body, he said aloud: "The beggar is dead. But, after all, he died fighting."

"It were better he than you," Ned heard a gentle voice say. Turning, he looked into the face of Judith, who with Rogers had landed from the raft. They had been brought by Birdmen to Ned's island to render assistance should he require it.

"Chief," said Ned, as he placed his hand gratefully upon the shoulder of the Birdman, "he has repaid his debt in full."

Judith, raising a white hand, touched the Birdman on his forehead and spoke a few words. Kneeling, he bowed his head to the rock. Then she motioned him to rise.

As Judith uttered these words they were startled by the distant flare of a rocket. It was followed almost immediately by the sound of heavy detonations. Jim's name came simultaneously to the lips of the three, for each realized he was in danger.

Ned sprang to his rocket-holder and an answering rocket hissed into the void. Judith ordered the Birdmen to get the raft under way, and a minute later they were speeding in the direction the flare of the rocket was seen.

With its crew of fliers spread fanwise, the raft made rapid progress. Its forward end rose until the angle became too acute to allow its occupants to retain their footing, therefore they were forced to adopt a prone position. Suddenly the pace slackened and the raft assumed its normal position. Looking upwards they saw that their Birdmen crew had dropped the lines and were catapulting downwards with terrific speed to a point not far ahead. Rogers, still retaining the spotlight, focused it near the spot at which the Birdmen aimed. He saw Jim standing at bay; his automatic was spitting viciously and at each shot an adversary crumpled. Jim was at one end of the raft and Rogers feared he would be attacked from behind and dragged backward, but the Birdmen soon dispelled all anxiety on Jim's behalf. Catapulting down, with their deadly spikes gleaming in the spotlight, they swept the Blackfaces from the raft while a welcome whirr of wings overhead indicated that reinforcements of their Birdmen friends had arrived.

The island which Jim occupied was in a somewhat exposed position on the right wing. He had just completed his preparations for defence, when the attack burst upon him.

The left wing of the Blackface army, under cover of the cavern wall, had been able to approach much closer to their objective without detection than the main body which was making the frontal attack.

They were within striking distance before they were located, and had sent a hail of missiles among the defenders, many of which took toll, but Jim, fortunately, escaped injury.

In answer to the Blackface attack, Jim fired his rockets into their midst, supplementing them by a fusillade of bombs. Those of the enemy who were within range fell hastily back and were immediately charged by the waiting Birdmen, but the following Blackface squadrons, who had escaped the effects of Jim's barrage, continued to pour in from the wing until it became impossible to fire the rockets or bombs without risk of injuring the defenders.

Hand-to-hand fighting became general, but the Birdmen, gradually gaining the ascendency, drove back the marauders. As the fighting receded, Jim was left practically alone. For the moment he, like Ned, became but a spectator of the rout of the Blackface horde.

The explosion of bombs and the firing of rockets from the other islands having ceased, Jim, becoming anxious regarding the welfare of his companions, decided to cross over to their islands and investigate. With this object in view he directed the Birdmen in charge of the raft to get ready to move. As the raft began to gather way an unexpected happening completely upset Jim's plans.

Swooping in from the now partially-exposed right wing, a scouting squadron of Blackfaces bore down on Jim's Birdmen, who, unprepared and too few in number to withstand the sudden attack, were speedily overcome.

Jim found himself in a perilous position. The Blackfaces, grasping the towing lines, swiftly changed the course of the raft to the direction from whence they came. Luckily, they had not attempted to come aboard. Jim's first care was to warn his friends of his predicament; he had no time to lose, as the raft was speeding at a rapid pace away from the island. Quickly placing the explosives and his automatic in a handy position, he next adjusted a rocket so that it would soar through the air in the direction of his abductors. Lighting the fuse, Jim crouched close to the decking and awaited results.

Presently the rocket shot upward. By its light Jim could see the whereabouts of the Blackface squadron; they were right in its path. As it passed through their ranks, they were thrown into confusion—their formation broke and for a few moments they darted aimlessly hither and thither, then, as if actuated by a common impulse, they plunged headlong into the lake. As they did so, Jim sprang to his feet and threw a bomb towards the spot where they had disappeared. Bomb after bomb followed in rapid succession, the disturbed water causing the raft to rock violently. Igniting a length of magnesium ribbon, Jim placed it in the rocket holder. Its rays would enable him to detect the presence of any lurking Blackface, but the light from the ribbon lasted but a few moments, and again he found himself at a disadvantage.

About to light another flare, Jim became aware of a movement of the raft. It had suddenly tilted to one side; a Blackface was climbing aboard.

Simultaneously with the appearance of a Blackface, a more welcome sight became manifest. In the distance a rocket flared. It assured him that assistance would soon be forthcoming.

The Blackface had now drawn his body from the water and was balanced on the edge of the raft, when Jim, trusting to the accuracy of a snap shot, pulled the trigger of his automatic. A look of surprise seemed to flit across the features of the Blackface; for a moment he retained his position, then suddenly his tensed arms bent and he slid silently back into the lake.

Hardly had he disappeared when other evil forms arose and the raft canted to one side as they climbed aboard.

Jim was in a tight corner, but the Blackfaces had made a tactical error in boarding the raft from one quarter instead of dividing their forces. If they had done so and attacked simultaneously on all sides, the issue would have been quickly decided. Jim's greatest fear was that they would attack from the rear. He momentarily expected to be pulled backwards from the raft, but the menace he was facing demanded that immediate and desperate measures must be taken. Lighting a short-fused bomb, he held it until the margin necessary for his own safety had been passed, then he cast it among the invaders. As the bomb left his hand, he jumped backwards into the water. It was his only chance. He was under cover not a second too soon, for hardly had his body become submerged when the explosion took place, and the blast passed harmlessly over his head.

Quickly climbing aboard again he found the raft had been swept clear of the enemy, but to his dismay he found that his stock of explosives had also been blown overboard. He had now only his automatic to rely upon. Luckily the magazine was nearly full, for the disaster that had overtaken their companions did not deter the remaining Blackfaces from again attempting to board the raft. Jim fired shot after shot point blank at his adversaries, but for one that dropped, two arose to take his place. At last, with several of the enemy still confronting him, Jim pulled the trigger of an empty weapon. Hurling it with all his force at the nearest of his attackers, he now stood at bay, unflinchingly awaiting the final onslaught. But it did not come. Instead, there came a mighty rush from the air. Jim had but a momentary glimpse of several dark bodies crossing his line of vision. Then his enemies, who had so sorely beset him, vanished, and once more he found himself standing alone upon the raft. He was bewildered at the sudden turn events had taken.

But a moment before sorely pressed, he now could hardly believe that the danger had passed, but when the raft drew alongside and Ned, jumping aboard, grasped him by the hand, he realized that he had indeed escaped his enemies.

The battle had been a strenuous one for all involved, and, with their nerves highly strung, the wanderers had no further desire for further encounters with the Blackfaces.

Although it was not probable that a renewal of the attack would be made, Rogers deemed it wise to make a speedy return to the Birdman City. Therefore, as soon as Jim boarded the rescuing raft, at a signal from Judith, it was taken in tow by the Birdmen escort, and the homeward journey commenced.

It was not long before they reached their destination, where they were greeted by a great concourse of the populace, who lined the way to Judith's palace. As they passed between the ranks the Birdmen bowed once more in homage and their chant of praise arose, swelling until its echoes came rolling back through the caverns of old Bal-yari.

CHAPTER XXII. — THE SPIRIT OF THE CAVERNS

THE defeat of the Blackfaces made it possible for the adventurers to enjoy a well-earned rest. Since their strange journey had begun they had passed through many trying ordeals, and if they were to win their way to the outside world it was necessary that they should conserve their strength. They had many discussions regarding their prospects of escape.

A week passed during which they explored the caverns in various directions. On these occasions they were accompanied by Oon, the leader, he being the greatest One or King.

It became apparent from observations made during these journeys that the Birdmen held sway over only a small area of this vast underground world, the extent of which, Rogers estimated, numbered many thousands of square miles.

He expressed the opinion that the absence of great rivers in the interior was due to the water filtering through the earth's crust.

"It is possible," he suggested, "that these great lakes and caverns extend under the ocean to the north-west as far as Asia, where the waters of the system are augmented by the melting snows of the Himalayas."

Even Judith, with her more intimate knowledge of the caverns, did not have any idea of their vastness. She questioned Oon closely with the hope that something he might tell her would indicate a way out, but Oon gravely told her that there was no known outlet.

With the aid of a torch, Judith endeavoured to demonstrate to Oon the effect of daylight in the world outside, her demonstration being followed with intense interest by the Birdman, who watched its rays as they flashed hither and thither. As he watched he seemed to be endeavouring to connect the flashing rays of the torch with something of which he had only a vague recollection. For a time he remained in profound meditation, then his face cleared and at length he spoke.

"The sleeper has awakened," he said simply. "I have been searching in the past and I have found something like that which you seek," pointing his claw-like finger at the torch. "Its light reminds me of the Great White Spirit of my ancestors which came through the wall of a far distant cavern many ages ago before the coming of the Great Serpent. It came from the father of the fires which you see yonder." Oon pointed to the distant lights which, shining like red eyes from the rocky islands, indicated the barrier between them and their enemies.

"After the coming of the serpent which barred the way to worshippers, the Great Spirit became almost forgotten, and now only remains as a tradition handed down through the ages, for no living Birdman has ever seen it or knows where it is to be found. It is only known that it shines somewhere beyond the serpent's abode; perhaps it may be found once more, and who knows but what it may be that which you are hoping to find."

After a pause Oon continued: "I will tell you how the Great Spirit was found and lost.

"In the dim past an exploring Birdman returned to his fellows after suffering dire privations in far distant caverns, with a story that he had seen the Great Spirit. So powerful was the Great One that the Birdman's eyes had been blinded, and the cavern had become brighter than if all the fires of the Birdmen had been lit in one place.

"When the Great Spirit looked upon him the Birdman threw himself downwards on the cavern floor, not daring to look him again in the face, and when at last he had the courage to rise, the spirit had vanished.

"The Birdman's story, when he returned, made such an impression that a party was sent to investigate, but, although they waited patiently, it was long before they saw the Great Spirit, and when at last he came his eye was so bright that none could look upon him.

"Thenceforth it became the custom for the chiefs to visit the cavern at certain periods when the Great Spirit came and looked down upon them. For ages this custom prevailed, until the coming of the first great serpent who took up his abode between the Birdman City and the cave of the Spirit and barred the way.

"Many tried to pass through to the cavern of the Spirit, only to meet death in the coils of the serpent. In time the Great Spirit was forgotten, and gradually the serpent became the object of worship. The Blackfaces, however, were the only race to set up the serpent as their idol, and to its shrine they brought sacrifices comprising their own offerings and prisoners captured in war.

"It is so even now. The Blackfaces still sacrifice to the serpent but the Great White Spirit is only a memory. Perhaps the Great Spirit still visits the cavern, and if you can safely pass the serpent and journey far enough you, also, might be permitted to look upon the Great One.

"I, Oon, will help you to find the Cave of the Spirit; when you have conquered the great serpent you will leave us and never return. I will be here, yet still be with you on your search. I will see the Great Spirit, then I will awake in darkness."

Judith, in her own words, translated Oon's story. Here at last was something, faint and nebulous, but still something upon which they could build their castle of hope, what though their castle came tumbling down about their ears. This hope of ultimate freedom was an ever-present buckler, warding off the mental menace that hopefulness begets in the brains of humans.

During her long three years' sojourn in the caverns Judith had not despaired of rescue. Miraculously her faith had been justified by the appearance of Rogers and the two boys, friends whom she loved. True, they were but unfortunates entombed like herself, but they, too, had faith and courage and the will to believe that they could conquer the darkness in the end.

When Judith had finished translating Oon's story Rogers removed the pipe from his mouth, and for a moment regarded it as if seeking inspiration from the curling smoke that rose from its bowl.

"There seems to be only one feasible solution," he at length ventured. "Long ago, far beyond the environment of the caverns frequented by the Birdmen, an aperture obviously existed in the cavern roof. It was probably a mere crack in the crust of rock, through which at a certain period of the year the sunlight poured. Possibly that opening still exists. What a wonderful sight it must have been to the Birdmen," he augmented, "and what wonderful luck for us to know about it.

"The old Birdman's assertion that the spirit was seen but periodically is useful," Rogers resumed. "It indicates that we must seek that opening wall in the south. The time for its visibility undoubtedly coincides with the longest day of the year, when the sun's altitude is nearest zenith, then through some gorge, or a flaw in the earth's crust above us, the sun's rays strike into the cavern. We will search for this outlet even though it will be a miracle if we find the one cave among thousands penetrated but once a year by a briefly lingering sun- gleam. Oon's cryptic utterance I cannot quite understand—'I will be here, yet still be with you. I will see the Great Spirit, then I will awake in darkness.'"

Rogers little realized how prophetic were Oon's words when he decided to follow this slender clue in the hope of deliverance.

CHAPTER XXII. — THE HAUNT OF THE SERPENT

PREPARATIONS for the journey of escape were completed, and an outline of their plans wirelessed to Mel. Now they were about to leave the friendly Birdmen who had succoured them when in dire need.

Judith had cast her lot in with her three friends. She could not now separate herself from them; she must share their dangers and what else might befall.

The Birdmen made no opposition when Judith told them that they were going to visit the caverns beyond that of the serpent. The Bird people feared that evil place, but believed that their Queen and friends would rid the caverns of the scaly horror.

Oon offered to provide a guard to escort them through the caverns of the Blackfaces and to within easy reach of the serpent's cave.

Judith gratefully accepted Oon's offer, and explained to Rogers and the boys that nothing would induce the Birdmen to proceed farther.

The serpent was their greatest terror. Fear greater than that of death seized them when the dreaded monster roamed the caverns. Then, panic-stricken, possibly hypnotized, the Birdmen were rendered helpless to combat their terrible enemy, and became easy victims for the marauding reptile that slaughtered or maimed every living thing it met or intruded on its haunts.

The departure of the little party was the occasion for a great demonstration by their strange hosts, who assembled on the shore of the little bay where they had originally landed. A solemn chant re-echoed through the caverns as the adventurers started.

Oon led a strong escort. The Birdmen whose task was to tow the boat and raft were commanded by the Birdman freed by Rogers, and who had been instrumental in saving Ned's life during the recent battle.

The gear had been divided between the two craft, thus providing ample room for the comfort of their respective occupants. Good progress was recorded when, some hours later, their first camping spot was reached.

After a hearty meal had been eaten, Judith intimated that she had something of interest to show them.

"Bring along your torches," she admonished them. "You will need them where we are going."

Oon led the way, and soon the nebulous light which had filled the caverns during their journey gave place to complete darkness. Their way led through numerous dry caverns; then they entered a narrow passage. It widened as they proceeded, until at length it broadened out to a large cavern, through whose centre flowed a stream. Taking Jim's torch, Judith approached the cavern wall.

"Look!" she exclaimed. "Here I procure the metal for my cooking utensils and ornaments."

Under the torchlight, Judith's storehouse presented a wonderful sight. An outcrop of almost pure gold protruded from the water-worn walls of the cavern.

Judith without emotion pointed to the fabulous wealth exposed by the rays of the torch.

"There are tons of gold in that vein," she said, "and I can show you a dozen others like it. These caverns are full of golden treasure. Look again!" Judith had approached the stream and, stooping, picked up something resembling a stone, in shape not unlike a large pear. "This is gold also," she said, as she handed it to Rogers. "The bed of the stream is literally paved with it."

Amazement and incredulity were reflected on the faces of her three companions, so suddenly confronted with such an unbelievable quantity of the precious metal.

Taking the nugget from Judith's hand, Rogers appraised it. "Three and a half pounds weight of pure gold," he opined.

Following Judith's example, Ned and Jim picked specimens from the bed of the stream. Scooping up some cupped handfuls of sand they found it impregnated with fine gold and pellets the size of a bean. Even the sands of the stream were of gold.

Sufficient gold lay exposed in that cavern, if it were possible to transport it outside, to upset the monetary systems of the world, for gold as a medium of exchange would be valueless.

Realizing their inability to take toll of the wealth strewn before them, they each selected a small nugget, smooth and water- worn, which could be carried without being burdensome. Then they retraced their steps to the camp.

Long hours after their departure from the Birdman City they found themselves approaching their destination—the Cave of the Serpent.

They had passed safely through the caverns of the Blackfaces without molestation. The presence of Oon's bodyguard, and a wholesome respect for the bombs which had wrought such havoc among them during the battle, prevented the Blackfaces from becoming demonstrative.

Small parties were seen on various occasions, but they kept at a safe distance, and made off whenever Oon's escort became inquisitive regarding their intentions.

Judith now received warning that the Birdmen did not wish to proceed further. Oon dropped to the water alongside Judith's boat and entered into conversation with her. After a brief interval Judith turned to Rogers and said:

"Oon informed me that they are about to stop and make camp, as this is the furthest they will go towards the serpent's cave. They are not going to desert us, for it is their intention to remain in the vicinity of the camp to guard us against attack by the Blackfaces. If they return now, it is probable that the Blackfaces, finding us alone, would harass us. The Birdmen will therefore remain until they feel assured that we have evaded the serpent. If we do not succeed in doing so and have to return, they will escort us back through the Blackface caverns.

"Oon advises us to make our camp well away from the water, as we would be completely at the serpent's mercy if it made an attack from the cover of the lake. He also described the shore between here and the cave. It is all flat sand-covered rock, and the distance is not great. Oon, measuring the distance in wing beats, estimates that it is about two miles from our present position. We had better land at once," Judith concluded.

Rogers gave his assent and Judith gave a word of command to Oon. The leader rose in the air. Almost immediately afterwards the boat and raft were turned shorewards, and within a few minutes they reached the landing place.

Where the landing was made the shore sloped gradually upwards. At the top of the rise the way became level, and the rock floor was carpeted with a thick layer of white sand abundantly interspersed with shells. It was thus evident that the flood waters did not rise as high as the plateau on which they made camp, the site selected being about three hundred feet from the water's edge.

Judith cautioned the party against making any noise that would warn the reptile of their presence. Even a whisper might be sufficient to put their enemy on the alert. They were now camped within the gates of its haunts and the plateau was probably one of its favourite resorts.

Judith's assumption was almost immediately verified, for a scout returned and reported finding numerous markings in the sand which indicated that the monster had been recently in the vicinity. This news was not unexpected, and steps had been already taken to guard against attack. To Rogers, Jim and Ned, watches were allotted, and Birdmen were posted at intervals round the camp.

No fires were lighted, and when a meal had been eaten those who were not on guard took what repose they could in such sinister surroundings. The men rested with their bombs within easy reach. The stillness was uncanny. A brooding presence seemed to be watching them—unseen, yet exerting over them an influence that chilled their hearts.

The Birdmen sentinels crouched motionless at their posts with a nameless fear in their eyes as they peered into the darkness. Yet the hours passed without anything untoward happening. With the coming of the waking hours courage returned. A period of action heartened them, commencing like the dawn of a new day.

Speaking in whispers, the four venturesome whites made their plans for the attempt to pass without an encounter with the serpent. It was not their desire to attack the reptile unless forced to do so, for they hoped to be able to pass through without the necessity for an encounter taking place. It was very difficult to decide which was the best course to pursue.

At last they decided to make preliminary surveys of the surroundings and of the serpent's haunts, by way of the lake. It was vital that this should be done quickly and silently. Therefore, the boat was chosen in preference to reconnoitring from the plateau. Also, by using the boat, they would be able to ascertain if they could pass without having to enter the cave.

Although they could not obtain any definite information from the Birdmen as to whether the lake near the cave was navigable, the fact remained that the serpent had prevented the Birdmen from making their pilgrimage to the cavern of the Great Spirit, which indicated the presence of a barrier in the lake at this point.

A decision was finally reached. Rogers and Ned would take the boat and investigate, while Jim and Judith guarded the camp. When they set out on the perilous errand they were well prepared for eventualities.

The boat glided silently towards the cave, its occupants keyed up to a high pitch of nervous tension. They knew not at what moment the thing they were seeking might attack them. So cautiously did they proceed that it was a full hour before they reached their objective.

They had not seen or heard anything calculated to alarm them. From the water they could see that the plateau ended abruptly against a wall of rock which, like a gigantic partition, divided the cavern as far as the lake. The only visible opening was at the northern end, which resembled the entrance to a huge railway tunnel. The lake, on the southern side along which Rogers and Ned had paddled for two miles, was fully twenty feet below the level of the plateau. The cliffs were perpendicular and without foothold.

Keenly they examined the rock wall facing the lake. Somewhere behind that wall the serpent lurked. Turning their attention again to the lake, they found it impossible to proceed farther, for the water ahead was dotted with pinnacles like those of the Devil's Maw through which they had passed earlier in their journey. There was a difference, however. Here was not the intense darkness they had experienced when navigating the Maw. The rocks were closer together, and navigation by a craft of any description was impossible. Of what was behind this forbidding barrier there was no indication.

The discovery of the barrier explained the reason why the Birdmen were forced to make their way through the cave. It also explained why the Big King Fellow had followed the same path. As they gazed upon the scene both men visioned the great flood upon which Judith had been carried over these cruel rocks. How she had survived they could not understand. Possibly the Big King Fellow reached this point when the lake was at normal height, and forced him to make his way along the shore and through the cave where he had obtained the pearl. Their investigations left two alternatives. They must either face the serpent or return to the Birdman City. The latter choice was unthinkable. There was but one way—forward. They would advance whatever the consequences.

Having obtained all information available, Rogers and Ned returned to the camp, where their appearance was hailed with relief. Their report was eagerly listened to, and when all had been told, preparations were made for an advance along the plateau.

Rogers' forethought in providing wheels for the boat now stood them in good stead. It was speedily fitted for the journey overland. The heavier portion of their equipment, including the outboard motor, had been left behind at the Birdman City, but they had brought with them their full supply of explosives and ammunition.

An hour following the return of Rogers and Ned, all was ready, and after Judith had spoken to Oon and conveyed to him their regret at parting from such good friends, they set off with a grim determination to win through to their objective, the Cave of the Great Spirit.

They regarded the ray of sunshine as a beacon set to guide them to freedom. It was something to toil for. A goal towards which they must struggle with all the energy they possessed.

The going over the loose sand was comparatively easy. They took turns at the pulling ropes, one always walking ahead of the boat as scout. They rested often, as they did not wish to overtax their strength in view of the ordeal awaiting them. Two hours brought them without incident to the great dividing wall, and there, slightly to the right, they saw the dark opening which they knew to be the entrance to the serpent's domain. Momentarily they paused. Then, impelled by a grim determination, they advanced into the dreaded cavern. As they passed through the opening a cold shiver gripped them. There was something so horribly sinister about the place, that it was impossible not to feel its influence.

As they entered they noticed that the sand was piled in long ridges, the rock showing bare between, while at the entrance the sand had been swept aside. They knew full well what this meant. They were treading the trails made by the serpent or whatever the denizen of the cave may be.

The roof of the cavern was not more than ten or twelve feet high, and was flat as the ceiling of a room. This feature explained why the Birdmen avoided it. There was not sufficient head-room for the use of their wings, and on foot they would be easy prey when attacked, their lumbering movements placing them at a disadvantage when opposed to their enemy, whose progress was reputed to be extraordinarily swift.

As the party proceeded they examined the walls, passing several openings, which imparted an uncomfortable feeling that attack might come from the rear. Their fears were well-founded, for presently they discovered a trail recently made by the reptile. The trail extended from an opening on the left across the cavern to a smoothly worn gutter that pierced the wall on the lake side. It led downward and was probably one of the short cuts to the water used by the serpent. This ramp sloped so steeply and the surface of the rock was so highly polished from long use, that to inadvertently step upon its surface would mean a sudden toboggan slide into the lake.

The utmost care was required to avoid these perilous places. Rogers led the way and with the spotlight searched every nook and cranny ahead. Armed with his Winchester, Jim acted as rear guard, while Ned and Judith kept the boat slowly on the move. It was tiring work, but Judith did her share of toil without a murmur. Thus the minutes passed without event. Nothing was to be heard but the crunch of coarse sand underfoot, or an occasional creak from the boat when some extra strain was put upon it.

If the four venturers to that awesome place could have looked beyond the wall on their left, or had they explored one of those sinister openings, they would have had added reason for apprehension.

In a cavern reached by a tunnel which led from the larger passage which they were traversing, a shape blacker than the surrounding darkness came suddenly to action. A hideous head lifted and commenced swaying slowly to and fro. Almost imperceptibly a huge body uncoiled. The fearful head flattened towards the sand of the cave.

Without a sound the reptile moved slowly forward, merely a shape moving like a passing shadow. Two points of baleful green light marked the head of the horror. Onward it moved with purpose implacable as Fate. It had sensed the presence of a victim. Another sacrifice had been sent to appease it. It need not hurry. Its victim could not escape. Down the tunnel towards the passage it glided, and as it emerged sharply to the right, the direction whence it could hear the crunch of sand, pausing with head alertly upraised, it waited. The crunching sound ceased.

A flash! A roar! A stinging pain, something it had never felt before, seared the neck of the waiting monster. Another flash, another stinging sear of flesh. Maddened, the reptile launched forward. Flash! Pain! Flash! Red hot needles plunged into its body. Rage, awesome in its intensity, surged through its sinuous length. The sand-covered rock was lashed as if by a mighty flail.

Still more flashes, then a reverberating roar close at hand made it stay its course. Twisting with the speed of lightning, its huge bulk swept round, sending the sand flying in a blinding shower. Again it slewed and faced the enemy. With head flattened against the cavern roof, body arched, the reptile surveyed the situation and appraised its assailants from its vantage point.

Again those stabs of pain. The great body tenses, the head moves angrily back and forth, its eyes are fixed on one point— that whence the flashes come. The tormentor is there. The green eyes have marked the enemy. Down swoops the head, drawing back as it descends. Then the tensed coils release their latent power, and the serpent hurtles forward with irresistible force to within striking distance of its intended victim, only to be cheated of its prey at the last moment.

Something has happened. Momentarily the enemy disappears. The green light has vanished from one of the baleful eyes. It cannot see so well as formerly. A sweep of the body and its attacker is disclosed again. The folds are about to encircle him, when another figure crosses the reptile's vision. Making no mistake now, with lightning speed the reptile threw a coil around the intruder. A sudden tightening, then a lifeless body fell limply to the floor of the cavern.

Moving cautiously in front of the party, Rogers presently discerned a shape stealthily emerging from an aperture in the wall on the left. Halting, he gave warning to those behind to be on the alert. Two points of light now became visible, swaying rhythmically from side to side. He knew that they were the eyes of the serpent. Keeping his gaze fixed upon them, he slowly retreated until he came in contact with the others. Without turning, he called softly:

"Pass the word to Jim to bring his rifle!" In a few moments Jim was at his side.

"The brute is just ahead lying in wait for us—not more than a hundred feet away," replied Rogers.

"Look!" Rogers directed Jim's attention to the points of light which were still plainly discernible. "Its eyes," he cautioned. "Make them your target, but do not fire until we place the boat in safety."

"Stay by the boat, Judith," Rogers advised. "It will afford some protection. Use your bombs if it approaches, but we will endeavour to prevent it coming this way."

Rogers and Ned rejoined Jim, who had steadfastly watched the green orbs of the reptile as they swayed ceaselessly to and fro. It was providential for Jim that Rogers and Ned returned so speedily, for he was beginning to feel the hypnotic influence exercised by the monster.

As they reached his side, Jim shook off the feeling of lethargy which had been slowly creeping upon him. Instinctively, with the reaction, he brought the rifle to his shoulder, and the pencil point ray of light to bear on the head of the reptile. As the ray crossed its vision, it moved its head angrily, and Jim found it difficult to get the sight he required. Presently, at what he considered to be a favourable moment, he pressed the trigger.

Again and again he fired at the elusive mark, his bullets apparently not making any impression upon his antagonist. Suddenly he lost sight of the reptile's eyes, and the next moment a terrifying shape hurtled towards him. It was almost upon him when a deafening detonation sounded a few yards away. Simultaneously the monster swerved, a hand grasped Jim by the shoulder, and a voice shouted:

"Run, Jim! Run!" It was Ned who had given the timely warning. Back towards the boat they raced. Reaching it, they were joined by Rogers.

Jim slipped a fresh clip of cartridges into his magazine and again sighted for the gleaming eyes which were now shining from near the roof. Flash after flash came from his Winchester, then once more he lost sight of the baleful eyes, and once again the thing was almost upon him. In another moment its folds would encircle him. There seemed to be no hope of escape. Jim fired his last shot point blank at the hideous head, now only a few feet away. Then a diversion came. A figure interposed between Jim and his opponent. Jim did not have time to identify the newcomer. Which of his friends had sacrificed himself for his sake? He could not tell. He only knew that a feeling of extreme nausea came over him, then a sweeping blow sent him headlong. Finding himself being hurtled down a decline which sloped towards the side of the cavern, he clutched at the rock in an endeavour to arrest his downward progress. Suddenly the cave vanished. He was shooting down through one of the black openings in the cavern wall on the lake side.

Presently the friction of his body on the rock ceased and he was falling through space, then, splash! he had fallen feet foremost into the lake. Rising to the surface, Jim found himself in a pool surrounded by rock pinnacles. It was irregular in shape, the size of a large swimming bath. Although shaken by his recent alarming experience, Jim was none the worse for his adventure, and promptly directed his attention to find the best way out of his scrape.

An examination of the pool disclosed a narrow channel, free from obstructions, running along the foot of the wall. It was the only passage through which he could swim safely. Jim realized that he had fallen through one of the openings used by the serpent when entering the lake. The thought for a moment caused him uneasiness. What if the monster, seeking escape, followed?

Unselfishly Jim hoped it might, for the sake of his friends in the cavern. At the thought of them, came remembrance of the tragedy. Which one of them had made the sacrifice in order to save him from the monster? Was it Rogers, their sturdy friend in every need, or Ned, his adopted brother and pal? His blood chilled at the thought—maybe Judith. It was too horrible to contemplate.

Jim had had only a fleeting glimpse of a crushed body falling to the floor of the cavern before he was swept aside like a straw. Less than a minute had elapsed since Jim had fired his last shot into the head of the reptile. Now he was listening to the sounds of the conflict still raging in the cavern. Bomb after bomb exploded and the sound poured through the opening to go rolling down the caverns until it became a distant rumble.

Now a much louder report reached him, followed by a thudding noise overhead, then a terrific splash signified that a heavy body had fallen into the pool. The water rose in the channel in a wave, then a mighty splashing commenced.

Jim's half-formed wish had been fulfilled. The serpent had arrived to keep him company. The channel was no longer safe. At any moment the reptile might come surging down it. Jim made for an opening between two rocks and squeezed himself through and, under cover, he waited for events to happen. The splashing continued, accompanied by a hissing noise. Then a period of comparative quiet ensued, to be broken presently by a renewal of the disturbance.

Jim reasoned that the monster must be badly injured. He fervently hoped that this was the case, but did not dare to take the risk of investigation. He had had quite enough of the serpent at close quarters to last him for all time, and nothing was to be gained by looking for further trouble.

Jim re-entered the channel and proceeded to put as much distance as possible between him and the loathsome occupant of the pool. Swimming steadily, he at last threaded the maze of rocks. The channel, though narrow, was well defined, and ultimately brought him to the open waters of the lake. When Jim reached the open water, he sought a resting place on one of the outer rocks, fortunately finding a small ledge upon which he was enabled to obtain a foothold. While resting he surveyed the situation. The Birdmen's camp was two miles away. There would be no difficulty in reaching it, as he could easily swim the distance. Jim would have welcomed a shorter route by which he could rejoin his friends, but, scanning the precipitous cliff which determined the limit of the plateau, he knew he could not hope to scale it.

Jim's thoughts were for his friends. He pictured the anxiety occasioned by his sudden disappearance, yet he was almost afraid to meet them. The memory of the figure encircled by the serpent's coils haunted him. He endeavoured to persuade himself that he had been tricked by some freak of imagination conjured up by the proximity of the serpent, but, try as he would, he could not banish the scene from his mind.

One of his friends had died, but who? With uneasy mind, Jim plunged into the lake. He would make the journey to the Birdmen's landing place as quickly as possible, then, two miles back over the sand of the plateau and he would know the worst. Swimming steadily, he at length made the landing place. On the top of the slope the figure of a sentry could be seen, which indicated that the Birdmen were still in camp.

Within a few minutes he arrived in their midst. Surprise greeted his appearance. The Birdmen grouped about him as he tried by signs to explain that they had fought the serpent. Oon and Rogers' Birdman friend were not to be seen. Again by signs Jim endeavoured to learn of their whereabouts: At length he was understood, and the Birdmen made a sweeping gesture which embraced the whole plateau. Jim was not any the wiser. Their actions simply indicated that the two Birdmen had gone away.

Failing to obtain further information, Jim set out on his tramp back to the cave of the serpent. Half an hour's walk brought him to the entrance. Entering, he gave a lusty coo-ee and listened. Presently back came the echo mockingly, followed immediately by an answer. It was a girl's voice and Jim knew that at least Judith was safe.

Oon, with Ned's rescuer, had watched the party depart. They knew that their friends were adventuring where death lurked, but the Birdmen were powerless to prevent them. As they watched them vanish in the gloom, Oon looked questioningly at his companion. Then they moved silently towards the outskirts of the camp beyond the cordon of sentinels. Rising in the air, they flew in a half- circle in a direction that would bring them to the tunnel's mouth without being seen or heard by the party toiling across the sand of the plateau. They reached their objective before their friends had covered an eighth of the distance.

Entering, they pressed forward resolutely, two dark shambling figures intent on some purpose of their own, their restless eyes searching every nook and cranny of the cavern as they advanced. It must have been some irresistible impulse which induced them to venture into the domain of the serpent. No Birdman had ever willingly entered its haunts since the time, far distant, when the only survivor of a band who had made the venture returned with the story of the killing of his companions by the serpent, and with the pearls which now graced Judith's throat.

Steadily making their way forward, they had penetrated far into the tunnel when they heard the now familiar sound of a rifle shot, followed by others in quick succession. Halting, they looked at each other. A shadow of disappointment crossed their faces. Then they started to retrace their steps. That shadow of disappointment which momentarily flickered in their eyes, explained why they had braved entering the serpent's haunts. They had set out to find and attack the serpent before it could injure their friends, and in so doing, they proved that they possessed the highest form of courage, that which makes men go forward even when they know that death may await them at their journey's end.

While still a considerable distance from the scene of conflict, the keen eyes of the Birdmen discerned the combatants. They saw the monster whirling, twisting and catapulting its huge length within the confines of the cavern, in an endeavour to destroy its attackers. Nothing daunted, Oon and his companion kept steadily on until they, themselves, became involved in the sanguinary conflict at a moment when the life of one of their friends hung in the balance. Oon's companion, seeing Jim's danger, without a moment's hesitation sprang across to meet the oncoming monster. With lightning rapidity he whirled his throwing club, and as the monster came within reach, brought the heavy weapon down with a mighty blow upon its head. So fierce was the stroke that the iron knob and part of the shaft was buried in the reptile's skull.

It was a gallant effort, which achieved its purpose—that of diverting the reptile's attack. With the club still buried in its head, the monster slewed to one side, then, with the speed of thought, circled round its victim. The coils contracted and Oon's gallant companion fell, crushed and lifeless, to the sand of the cavern.

Jim had disappeared, but with his last shot he had put out the remaining eye of the serpent. Blind now, its rage redoubled, it became a whirling mass of fury, hurtling up and down and from side to side of the cavern, blinding showers of sand following its every movement.

Rogers, Ned and Judith were still endeavouring to disable it. Whenever opportunity offered bombs were launched in its direction. For safety the three crouched close to the cavern wall near the boat. Time and again they escaped the menacing coils by inches only. Stricken with horror at the fate of their Birdman friend whose gallant act they had witnessed, they welcomed the appearance of Oon, who, disdainful of danger, stood leaning on his club, watching the blind fury of the reptile.

It seemed impossible to kill or even disable the monster. Although riddled with bullets from Jim's rifle, and still carrying the club embedded in its skull, no diminution of its vitality was apparent. If only a lucky bomb would strike it in some vulnerable part!

Jim had disappeared. Their calls had been unanswered, and they feared for his safety. Oon, whose vision penetrated into the dark recesses, failed to locate him. Now, with back to the wall, they again awaited attack.

Once more the monster passed, then turned in its tracks. Straight towards them it came, closer yet closer. Judith shrieked. Her nerves were breaking under the strain; but the reptile turned and was making its way to the opposite side of the cavern. It had found the gutter leading to the lake. Already half of its huge bulk had disappeared.

At the same instant, a bomb containing two full plugs of gelignite left his hand. It landed in the gutter, and, rolling underneath the moving body, exploded with a deafening roar which shook the cavern. Fatally injured, the reptile disappeared into the dark waters of the lake.

CHAPTER XXIV. — LOOKING BACKWARD AND THE CAVE OF PEARLS

FREED from the menace of the serpent, their immediate care was to make a search for Jim. It was Ned who first suggested that he might inadvertently have slipped down the gutter into the lake. This seemed a possible explanation of Jim's disappearance. If he had escaped injury during the fight, a plunge into the lake would not be a serious matter.

Reasoning that they would probably find him safe, they returned to Oon, whom they found standing beside the body of his companion. At their approach, Oon, first pointing towards the tunnel's entrance, stooped, and without apparent effort, lifted the dead Birdman in his arms and then walked slowly in the direction of the entrance. He was taking the body of his friend back to the camp.

Rogers, Ned and Judith followed. They were going to search for Jim. The party had proceeded to within a short distance of the entrance when a vigorous coo-ee rang through the cavern. Three who heard it simultaneously uttered Jim's name in tones of heartfelt relief. Then Judith gave a call in return, and a few minutes later Jim appeared out of the darkness. A look of surprise flashed across his face to find his three friends standing before him unscathed. He gazed from one to another in amazement until he caught sight of Oon, who stood silently in the background bearing his dead companion in his arms. Jim then realized who it was that had saved him from the serpent. The Birdman had given his own life for him. A wave of emotion shook Jim at the realization of the splendid sacrifice. Ned, too, was indebted to the dead Birdman, for he had saved him when attacked by the Blackfaces. Nobly he had repaid Rogers for rescuing him from the furnace of death.

It was with feelings of joy tempered with regret that the party retraced their steps to the entrance. Judith had spoken to Oon, and he had told her that when once clear of the tunnel, he would leave the body of his companion with them, while he returned to the camp to obtain the assistance of the Birdmen. They would take it back to the Birdman City, together with the remains of the serpent, if, as they hoped, it was dead, to be burnt in the fiery crater. They could not leave it to decompose in the water, for out of the waters came their chief sustenance. Contamination meant pestilence, and the laws of the Birdmen were so rigid in safeguarding its purity that any breach of the law was punishable with death by fire.

Upon their arrival at the entrance, Oon immediately flew away on his mission. After a while the sound of many wings was heard and, led by Oon, the squadron of Birdmen arrived. They formed up along the edge of the plateau overlooking the lake and waited until the raft, which was destined to be the funeral barge of the ill-fated Birdman, arrived.

Once more lifting the body, Oon stalked to the edge of the cliff. Standing for a moment on the extreme edge, he spread his great wings. Then, with a spring, he launched himself into space and dropped lightly to the raft. Depositing his burden upon it, he immediately returned to the plateau, landing at Judith's side. He then issued a command, and the Birdmen formed up in two lines in front of Judith. Oon placed himself at their head. At another command their wings spread in perfect unison, then closed again. Three times this was repeated.

"The salute to the dead," Judith softly replied, "and it is also a farewell salute to us who continue on our journey. They believe our departure is like death, and that we go to return only in the spirit. Whether it is a good or bad omen I cannot say."

The Birdmen now formed a circle with the four whites in the centre. At first there were intervals between each Birdman, but the circle slowly closed. When the Birdmen touched wing to wing, one in every three stepped forward, thus making a second circle. The same process continued until there were five circles. Oon and three Birdmen now stepped to the centre.

"We, too, with the three Birdmen must form a circle, the sixth. Oon will take on the centre. Look, he is ready. When he gives a sign sit down on the sand. I have been through this ceremony before. Do not be afraid, although it is weird and terrible. We are about to be shown the world of the past."

Oon alone stood. Taking a small golden cup with a short hollow stem from his bag, he affixed it on the spike which adorned his head. Then, from the same receptacle, he produced a wondrous ruby, cut perfectly round and identical in size with the crystals used by clairvoyants. Placing the sphere in the cup where it glowed with a dull red flame, he commenced to turn slowly, his outstretched arms performing a sinuous undulating movement which infected the beholders with a strange fascination. Judith alone of the four white people who gazed with tense curiosity and wonder at the scene, had previous experience of the rite.

Slowly Oon and the sphere revolved, and as he turned, the rhythmic motion of his hands continued. One, two, three revolutions he made. It began to get monotonous. Would he never cease? Four turns he made with the watchers unconsciously following his every movement. The glowing ball on his head seemed to grow larger. It was twice its normal size now. It was becoming transparent. An extraordinary thing was happening.

Five, six turns and the ball had grown to immense proportions. It seemed to fill the cavern. In it were moving shapes. There were trees, mountains, flying things. At the seventh turn, Oon, the ball and the cavern vanished. They were in a great valley by a lake surrounded by a forest of mighty trees. The air was full of rushing things. From the waters of the lake came great monsters, creeping, crawling, winged reptiles. Giant crabs clawed their way out of the ooze. A perpetual battle was waged between the winged and the crawling reptiles. When a kill was made, a hooked beak, saw-like teeth and lancet-pointed claw tore at the victim until only the bones remained to mark the site of the sanguinary feast. Great vulture-like birds darkened the air. Enormous bats hung from the branches in the sombre recesses of the forest where the great trees fought their way up towards the sunlight. Tall and straight, they grew so close together that their branches, interwoven overhead, formed a canopy which excluded the light. There was no song of birds within its sinister shadows. Poisonous vapour filled the air. Fat, bloated vegetation grew amid the ooze, its leaves casting off a phosphorescent light, which, shining on the vapour engendered in the slime, peopled the place in wraiths.

Now from space they viewed a troubled earth. A mighty mountain poured forth smoke and flame beneath them. The earth quivered and ominous sounds were heard which grew in intensity until they resembled the staccato rattle of machine-gun fire. Louder explosions followed to die away in a low rumble. The air was oppressive, the sky sullen. Some cataclysm of nature was taking place. The earth was sinking, the mountain was torn asunder, and the forests were engulfed as the waters of the ocean poured over the land.

Again from space they watched another transformation. The waters slowly receded and once more the mountains reared their heads towards the sky, now ice-capped and desolate. The earth, frozen, lay under glacial ice of unknown thickness. Once more the scene changed. The ice has disappeared and now the fierce rays of the sun beat down upon swamp and river. The mountains no longer rear their heads skywards; they have been flattened almost to the level of the plains by erosion. Life once more appears; strange forms are seen emerging from great chasms in the earth. They wing their way hither and thither during daylight hours, to retreat when darkness falls to their underground haunts. Now the waters are with them in their lairs, enormous caverns extending for unknown distances in the bosom of the earth; caverns in which no floor was visible—only water.

Again a convulsion of nature: the earth quivers and all exits to the outside world are closed. The winged creatures, trapped within their mighty prison, fly aimlessly to and fro in the darkness. The next scene depicts a lone figure wandering amid the gloom. Suddenly he stands as if turned to stone; he covers his face with a webbed hand to shield his eyes from a blinding light which pierces the cavern wall. He prostrates himself face downwards upon the floor, and remains thus until the light has gone.

They saw the Birdmen who made pilgrimages to the shrine of the Great Spirit; the coming of the serpent which intervened between the Birdmen and their Shrine; the lone figure of the big king fellow, gaunt and haggard, making his way through the caverns; a flood on which was borne a tossing log, upon it and held above the seething waters in a friendly fork the form of a young girl; the meeting between Oon and the three white men; the battle with the Blackfaces, and finally the combat with the serpent.

The vision faded. Rogers looked at his watch, then glanced at his companions. "One minute exactly," he said in a matter-of-fact voice.

In that brief period they had looked back almost to the beginning of things. How many centuries it was impossible to compute. Yet by means of the occult power possessed by this strange race, an eternity of time had been condensed to a brief sixty seconds, in which the mysterious past had been revealed. The Birdmen were still grouped in a circle, and Oon still retained his place in the centre. At his signal the outer circle moved off into the darkness. Each circle followed in turn, until only Oon and the four whites remained. After speaking earnestly to Judith, Oon, with a farewell gesture, followed his companions.

The three men turned to Judith, and in answer to their inquiring looks she said:

"They go, never to return to us, but we will never be forgotten by them. Their power enables them to re-enact the scenes of which they and their ancestors have had past experience. But they cannot look into the future. From now on we are lost to them, but up to now, where we sit together on the sand, they can conjure up all the incidents in which we have taken part while associated with them."

As Judith concluded, Ned looked at Jim and at the same time brushed a hand across his eyes.

Jim nodded. "I saw it too, Ned. I seem to feel millions of years old. What about you, Chief?"

Rogers, thus appealed to, answered briefly. "Yes, boys; I, too, looked into the past, but we will have to forget these things for the present calls us. Come!"

Rising, they made their way back to the tunnel and soon reached the scene of the conflict with the serpent. The boat was found to be undamaged and ere long they continued on their journey through to the haunts of the serpent. They had not proceeded far when the tunnel took a turn to the south up rising ground. After a time it broadened out to a cave of large dimensions, in which the serpent's trails were clearly visible in the coarse sand.

Presently Rogers gave an exclamation. "We are in the Cave of Pearls!" he said. "Look!"

He pointed to the southern wall. Heaped against it was an immense quantity of mussel shell. From either wall the floor sloped to the centre, making a saucer-like depression devoid of either sand or shells. The rock which formed the saucer was worn smooth, evidently by the friction of the reptile's body. In the centre was a pot-hole the size of a cauldron, which was filled with sand and shells.

Rogers stooped and, dipping his cupped hands into the depression, allowed the sand to run through his fingers slowly. As the sand filtered through a pearl appeared, and as the last of the sand fell, exposed in his palm lay a thing of beauty. Judith and the boys gazed at the object reposing in Rogers' palm with astonishment. Perfectly round, it shone with a lustre that fascinated the beholder.

Judith complied and scooped a double handful as Rogers had done. Ned and Jim followed suit, and each secured pearls nearly equal in size to that first discovered. These pearls were larger than those worn by Judith.

"We will sift the contents of the pot-hole," said Rogers. "Get a piece of mosquito net from the boat, Jim."

Jim procured the net, also a cooking utensil to act as a scoop, and soon they were busy sifting. The contents of the pot- hole dwindled, while the number of pearls found grew apace.

"I am nearing the bottom," said Jim, as he once more dipped his scoop into the depression. As he spoke, he struck something hard with his implement, apparently an object too large to enter the scoop. Discarding the latter and lying flat, he reached down and brought forth a smooth object which proved to be a skull. As Jim lifted it, an enormous pearl fell from one of the eye sockets. It was the skull of a Birdman. Jim handled his grisly find with interest. As a medical student, he had no qualms in handling bones which probably had rested in the cup for centuries.

When Jim had completed his task three skulls lay exposed, and from each a great pearl had fallen.

"That is all, Chief," he said, after a careful examination of the cavity. "It is empty."

"Replace the skulls," said Rogers. "We will leave them where we found them. They are probably the relics of some of the victims sacrificed by the Blackfaces. Or else those of the Birdmen who were killed by the serpent when searching for the pearls now worn by Judith."

Jim placed the skulls back in their resting-place, and filled in the cavity to the brim with sand. They had found the Cave of Pearls in reality. In the folds of a piece of mosquito curtain reposed hundreds of the finest gems ever seen by human eyes.

Their value, if their discoverers were fortunate enough to be able to transport them to the outer world, would be fabulous. They would take them with them, for, unlike gold, the gems would not be an encumbrance, and perhaps some day they would astonish the world by being able to produce them as material evidence of the authenticity of their story.

However, after the first surprise, the discovery of the pearls did not arouse in them feelings of elation. The future was too clouded for them to indulge in undue jubilation. They had already found gold in such vast quantities that man in his most imaginative moments had never visualized. Yet they had left it behind with hardly a second thought. They had seen a ruby used as a crystal, which the world's wealthiest would be unable to purchase if resolved into terms of money value. They did not linger in the serpent's cave. The place was too gruesome. Evidences of past tragedies were on every hand, and it was with feelings of relief that they passed on, seeking a way out of a labyrinth in which they had now become involved. It was problematical, even if they desired to retrace their steps, whether they would be able to do so.

The way was difficult. Underfoot a thick layer of yielding sand made progress slow and exhausting. Their one thought was to reach the water. Once there, they could camp and rest. During the past hours they had gone through an ordeal which had not failed to leave its mark upon them. They looked weary and haggard. The healthy tan of their faces had given place to a transparent whiteness. Their pallor, however, did not indicate that they were sick physically. They needed rest. The strain on their nerves had almost reached breaking-point when Rogers, acting as advance guard as was customary, made the welcome announcement: "Lake ahead."

They were out of the labyrinth, yet before they could make camp a strenuous task was still before them. Emerging upon a plateau similar to the one already traversed, it was found that a tumbledown of boulders had to be crossed before the lake could be reached. In such a place the wheels attached to the boat were useless. The latter would have to be unloaded and the equipment transported by hand. It was not a pleasant prospect in their tired condition, but they had to tackle it if they were to camp at the lakeside.

Rogers had clambered down to investigate and returned with the information that beyond the tumbledown there was a flat space where camp could be made. During the last stages of the journey they had traversed rising ground, and from where they stood it was fully a hundred feet above water level. This point was the highest reached during their wanderings. The caves through which they had recently passed had been devoid of the nebulous light, but, being now accustomed to seeing in the dark, they had not suffered much inconvenience.

The scene before them wore a different aspect; for the waters of the lake could be clearly seen, so strong was the light radiating from the rocks. It seemed as if the first streaks of dawn were illuminating the lake. This welcome sight cheered the wayfarers. It made their task easier, and they tackled it with renewed vigour, with the result that in a comparatively short time their belongings were transferred to the newly selected camp-site. After Rogers had sent his message to Mel, too tired to eat, they lay down and slept.

CHAPTER XXV. — MER

ROGERS was the first to awaken. He arose and for a time stood gazing down upon the sleepers; then, putting his hand into his pocket, he brought out his old briar pipe, lit it and moved briskly to the boat. From a canvas pocket he brought forth Bal-yari's token and scrutinized it closely, afterwards consulting his pocket compass. He was so preoccupied that he was not aware that Ned stood beside him until the latter, putting his hand on his shoulder, inquired:

"Yes, Ned. I am endeavouring to find inspiration from old Bal- yari's token. Up till now it has proved to be remarkably correct."

With his finger he traced their journeyings up to the point where they were now camped, checking the various symbols shown on the token with the places they had actually seen.

"When we left the Birdman City, our course lay west-south- west, and when passing through the Blackface domain marked on the token with the rough drawing of the setting sun, our course became south-west. Passing through the cave of the serpent and up to the point of our exit at the top of the tumbledown yonder, we had been heading due south. Aided by our previous experience we assume that the two parallel lines commencing from the point where we are now camped, indicate a comparatively narrow lake or passage. At the end of the lines is another rough circle similar to that indicating the Whiteface and Blackface domain. We therefore can take it for granted that this circle also represents a lake.

"Within the circle a hole is cut in the token. What this represents is difficult to determine, but if my reasoning is correct we will find it represents the place where the Big King Fellow entered the cavern. This lake must therefore be almost directly below 'Blaircourt,' Judith's home, and is the lake into which she was drawn when the flood waters broke through. South of this lake we find other parallel lines and vague markings. The Big King Fellow must have first travelled southward, only to find his way barred. Retracing his steps, he discovered the system of lakes which led him eastward, and finally to freedom.

"The token only indicates the lakes actually traversed by him. I am convinced, however, that from the Blackface waters the system continues north. However, our course is southward. The country south of 'Blaircourt,' is mountainous. Rugged gorges, precipitous cliffs and heavily-timbered valleys are the predominating features of a stretch of country very little known. It must be somewhere in that region that we will find the ray of light. We have thirteen days in which to discover it. If we fail in that time we cannot hope to see it until another twelve months has elapsed."

Jim and Judith now joined them; for their benefit Rogers gave them a précis of his conversation with Ned. Judith listened intently.

"While you have been talking about the light, I have been dreaming about it," she said at last. "In my dream we had come to the end of somewhere, and we sat together hopeless and despairing in the darkness of the thirteenth day, when suddenly the cavern was lit by a wondrous ray. It seemed as if we had been guided to it by some unknown power. It vanished as suddenly as it came, and I awoke. Somehow," continued Judith, "I still feel myself to be under the influence of Oon's hypnotic power.

"In him, as Chief, is concentrated the thought force of the priest of the cult. It was for some breach of the cult law that the Birdman who was killed by the serpent was condemned to be thrown into the pit of fire.

"Mer was his name. He had no name when you found him, for it had been taken away from him. You might have noticed that he was never called by name even by me, and although he performed great deeds after his reprieve from death, he was not forgiven for the fault he had committed. But now he is dead; by his sacrifice he has regained his right."

"The name Mer," he said, "is familiar to me. It is the name of an island in Torres Straits, and is situated a hundred miles east of Thursday Island and about one hundred and thirty-five miles east-north-east of Cape York. It is now known as Murray Island, and is one of a group at one time inhabited by some of the most bloodthirsty natives known in those seas.

"Years ago I visited the island and made the acquaintance of one of the surviving priests. He was the Gogo, or chief of priests. From him I learnt many legends of the Mer islanders and obtained some insight into their bomai-malu cult, whose devotees practise the occult.

"These people possess wonderful hypnotic power, and when under the influence they are reputed to be able to visit other worlds. What I am going to relate may be only a coincidence, but it is a very remarkable one.

"One of their legends is that their ancestors were men with wings. They could fly, and lived in great caverns and subsisted on fish, even as the men of these caverns do to-day. Can there be any connection between the legendary Birdmen of Mer and the Birdmen of these caverns?" Rogers questioned.

"The present-day inhabitants of Mer still possess remarkable hypnotic power, and our Birdmen here in the cavern have recently given us a practical demonstration of the occult. I fought against Oon's power, but without success. I had always thought myself immune from influence of this kind. I have but a faint recollection of what I saw, but I seemed to see volcanoes belching forth flame and smoke, winged men and reptiles, great forests, floods and a quaking earth. The recollection is but nebulous, but my experience has satisfied me that the Birdmen possess abnormal psychic power."

Proceeding south, they passed along a river which at times broadened into lakes, the limits of which could not easily be determined, and when at intervals they camped for a much needed rest it was noticed that the character of the rocks had changed. Limestone now predominated and the roof under the rays of the spotlight revealed great clusters of stalactites. On the shores of the river stalagmites had grown up to meet them, forming great spike-ended pillars such as they had seen in the Cave of a Thousand Columns. These pillars reminded the wanderers of the old-time temples of the gods. Occasionally in mid-stream they would pass a lone rock rising above the level of the water. Presently the rocks became more frequent and the fairway became obstructed and difficult to traverse, but at last they found themselves paddling along a comparatively narrow channel, which, at its greatest width, was not more than ten yards. This channel was of great depth, and on either side the massive pillars rose majestically to the roof.

After traversing the channel for a considerable distance they suddenly arrived in broad waters once more. The pillars on their right, or west side, ended abruptly. Rounding the pillars, they perceived that the lake extended in a northerly direction. For a time they paddled northward along the shore, then once again the waters narrowed. Changing their course to west, they crossed the mouth of the river, which entered the basin, then continuing, they came to still another waterway entering from the north-west. It was evident that they had discovered the junction of many streams. Having reached the western limit of the basin they skirted the shore to the south, and presently the sound of falling water arrested their attention.

Paddling close in shore, a rock slide over which a small cascade was tumbling was discovered. A flash of the spotlight disclosed that the tumbledown extended to the roof and, jammed amid the rocks, could be seen the trunks of dead trees.

Rogers now remembered Bal-yari's token which displayed a circle with a hole on the west side. The truth suddenly dawned upon him. They were under the lake at "Blaircourt." It was here that the Big King Fellow of bygone days, and more recently Judith, had been washed into the caverns. How either of them had escaped death in the raging torrent of waters which had burst through he could not understand. Yet they had escaped, for Judith was there before them, and old Bal-yari's story and token vouched for the escape of the black king. Rogers looked at Judith who was sitting with her chin cupped in her hands, apparently in deep thought. She was strangely silent. As he glanced at her, she spoke in a low and vibrant voice which electrified her hearers.

Rogers felt a quiver pass through him at these simple words. Intuition, or something more subtle, had warned the sensitive girl that she was near to the ones she loved. Close, yet the utmost limits of the earth were closer to her than the place in which she now found herself. Within the confines of that sombre dungeon she was as far from them as the stars.

At Judith's remark Ned and Jim looked wonderingly from her to Rogers, who, himself about to break the silence, paused, for Judith was again speaking.

"I can see Oon," she said dreamingly. "He is pointing and saying: 'Go that way quickly.'" Slowly Judith's hand lifted and pointed south. "We must obey Oon and go quickly," she insisted.

Intuitively the keen brain of Rogers connected these words with Judith's previous assertion that she still felt under Oon's influence. He did not wonder at the dominance which the Birdman evidently exercised over her. She had been three years in the caverns, and it was inevitable that she should be influenced by a power to which even he had succumbed.

"I have been asleep and dreaming," she said. "I dreamt that I saw Oon. He was standing on the rocks before us and spoke to me. Pointing to the south, he said: 'Go that way and go quickly.' I looked in the direction in which he was pointing and saw a light. Presently it grew dim and at last vanished. Then I looked for Oon, but he also had gone. Then I awakened."

Perplexity clouded Judith's eyes as she continued: "I was near someone I dearly loved. I felt I was near home. Then Oon stood before me. He was very real. If I did not know that we would never see him again I might have thought he had followed us to give warning of impending danger. It seemed absurd to be frightened by something which may have no real meaning, but I am afraid."

Judith placed her hand on Rogers' arm, and, looking in his face, said earnestly: "Let us go."

Without further question, for Judith's entreaty seemed a command, the paddles were brought once more into action, and the boat moved rapidly southward.

CHAPTER XXVI. — PURSUIT

BROODING in sullen fury over their recent defeat, the Blackfaces plotted to wreak vengeance upon the white strangers, who, by the use of unfamiliar weapons, had contributed to their downfall. The killing of their idol added fuel to their wrath, which could only be assuaged by the death of the intruders.

Returning to their own domain after the battle, they had indulged in an orgy of slaughter and feasting, the victims being a number of Whitefaces who had fallen into their hands. Their cannibalistic rites were accompanied by scenes of unspeakable horror and cruelty. They had brought the killing of their enemies to such perfection that every agonized gesture of the victims was a stimulus which lashed them into a state of diabolical ecstasy. When the writhing of their victims' pain-racked bodies had inflamed them to the verge of madness, the signal would be given for the final and crowning act of horror.

A great amphitheatre, into which these hideous monsters crowded until there was hardly moving space between their noisome bodies, was the scene of the sacrifices. Black shapes, bat-like, clustered on every ledge or hung from projections on the cavern walls. With slavering mouths and rolling eyeballs, they watched and waited for the flutter of death.

It came. A head rolled to the cavern floor, and a grotesque body with beating wings reeled drunkenly about the blood-stained rock. Other heads fell in quick succession, and each body in turn joined in the flutter of death and danced until the quivering muscles grew lax. Then one by one they crumpled to the rock, and as the last hapless victim fell the evil horde with a roar of guttural mouthings hastened to the feast.

Later a flight of Blackface warriors passed westward. They were on a mission of vengeance. With passions inflamed against the destroyers of their idol, they exulted in the knowledge that without the assistance of Oon and his bodyguard the strangers would fall an easy prey to the attack.

Plans for their revenge had already been formulated, and they looked forward to the time when they would subject their victims to the dread ordeal of the flutter of death with its gruesome aftermath.

Their progress was rapid and soon the tunnel was reached. Alighting, they passed through and found the camping place lately vacated by their quarry.

This discovery gave them intense satisfaction; they were hot upon the trail and soon would come within striking distance. Continuing their flight, they at length reached the column-girt channel. Arriving at the broad waters, they were at a loss as to which direction their enemies had taken, and attempted to solve the problem by a circling flight over the course taken by Rogers, which, as related, crossed the mouth of the two rivers and turned south.

But the Blackfaces hesitated. Their leader was undecided what to do. Would he fly southward or turn north again? Impatiently he darted hither and thither until at last, after issuing a command to his Blackfaces to follow, he turned and winged quickly northward, and for a time at least the whites were safe from pursuit. But for how long?

A single drop of water formed upon a small stone embedded in the strata of the roof of the cavern whence Rogers and his party had so hastily fled. Slowly it attained weight. Fed by an almost imperceptible trickle which percolated from above, it clutched the pointed end of the stone with limpet-like tenacity until the law of gravitation caused it to break away with a final quiver, and fall into the basin below.

For centuries Mother Nature had been waiting for that tiny drop to fall. The patience of a thousand years had been rewarded. Its falling was to be the forerunner of momentous happenings, for faint tremors shook the earth, and upon the small stone another drop quickly formed and as quickly plunged into the lake below.

Drop followed drop in quick succession until an unbroken stream poured from the stone. The downpour grew in volume. Pieces of earth in which the stone was embedded were washed away. Its hold weakened. The stone, too, falls. Ominous sounds accompany its descent. The caverns become filled with vague mutterings, and the once placid basin is troubled by the falling debris.

At the point where the stone once clung, an opening appears, and from it a cascade thunders into the lake, increasing in volume each moment. From other portions of the roof similar streams issue. The earth movement above becomes more pronounced. Then, accompanied by a roar as if the parked artillery of the world had simultaneously fired a salvo, the roof crashed into the lake below.

Forced aside, the waters rose in a mighty wave and swept with irresistible force through the caverns, heralded by the shrieking of an air-blast, which, as it tore through the underworld, lashed the placid lake into whirling foam.

The four white people had put as much distance as possible between them and the junction place of the rivers. At no period during his wanderings in the caverns had Rogers felt so great an uneasiness. Ned and Jim were likewise affected. It seemed to them that the most crucial period of their enforced stay in the caverns was approaching. They fled, from what they did not know. The air seemed pregnant with menace. Straining every muscle, they kept the boat, hour after hour, on its course southward. With short stoppages for rest they paddled on. Forty-eight hours later they stopped—weary and fatigued in body and mind—at what seemed to be a dead-end.

During their flight they had passed rivers which branched on either hand, but adhering to their decision to proceed due south, they had not ventured to deviate from the set course. The waters which they had traversed for so many hours at length narrowed to a swiftly-flowing, treacherous stream, difficult to navigate. The risk of continuing became apparent to the three.

The boat had arrived at a rock wall which jutted out into the stream. Around its outer point the current ran swiftly. Rounding the point, they found themselves in a pool sheltered from the rushing waters, situated at right angles to their previous course. Paddling for a space of fifty yards along the inner side of the rampart, they reached the shore.

The boat was paddled alongside a flat rock and the party disembarked at the foot of what appeared to be a rock stairway formed of boulders. A flash of the torch disclosed a dark opening at the top. After a hasty conference, it was decided to abandon the boat and explore the opening. To unload the boat was the work of but a few minutes. Then, with as much as each could carry the ascent began. It was slow, laborious work climbing the slope, but at length they reached the dark patch near the roof and found themselves at the entrance of a gallery.

Three journeys were made before their belongings were all at the top. Then they hauled their boat up the stairway, and finally a supply of water was procured. They had barely completed their task when, preceded by violent gusts of wind, a menacing roar sounded. Nearer, closer it came, growing in intensity each moment until far below them came a resounding crash which shook the very rocks upon which they were standing. A wall of water struck the natural rampart behind which they sheltered. Barred, hurled back, the torrent rose to the roof. Surging past the obstruction, the flood was transformed into a huge whirlpool which sucked the waters of the little bay into its maw as it gyrated onwards.

Startled by the rush of wind, the party threw themselves face downward on the rocks. For a moment it seemed as if they would be lifted bodily and carried away before the blast, but the wind ceased as suddenly as it came, and after the tumult a dead silence reigned. Their first thought was for the stores and the boat. Their gear was found to be quite safe. But the boat had been caught up like an eggshell, tossed against the cavern wall, and left twisted and broken beyond repair.

As they looked upon the wreck of the frail craft which had carried them so far, despair flooded their hearts. In their boat it might have been possible to have returned to their starting place and there wait until friends outside could tunnel through to them, although they realized that even that chance of succour would have been a slender one.

"So that's that," he remarked with a grim smile. "Well," he continued, looking at the wrecked boat, "it has carried us far, and we could not foresee this calamity. It makes our position more precarious, for if we fail to find an outlet our case will be indeed serious."

His companions fully realized the gravity of the position. Without the boat a return to the Birdman City seemed practically impossible. Still, the Big King Fellow had done so—had set a precedent—contrived to make the journey. How, they wondered, had he done it? Anyway, if a black man could surmount these obstacles, well, they could do the same, they reasoned.

In any case, they had not yet attained their objective. They must go on whether success or failure was the ultimate result.

Not many hours remained of the allotted time at their disposal. From where they now stood the final stage of their journey would begin. They must not waste time. Even minutes were precious. Silently they made preparations for their final trek. Everything not absolutely indispensable was discarded. They packed all that remained of their explosives, also the ropes, a rock drill and sledgehammer. The wireless set was also retained; in the event of failure a last message could at least be sent to their loved ones.

With sufficient water and food to last them for some days they started. Shouldering their burdens, they stumbled over the rough floor on yet another venture into the unknown.

CHAPTER XXVII. — BAULKED

IT was not long before the Blackfaces discovered that they were on the wrong scent. When this fact became known the leader sullenly gave the signal to return.

Baulked, they turned south again, and when within a few miles of the meeting place of the rivers they were dismayed by the thunderous sound caused by the collapse of the cavern roof. The resulting air blast scattered the flying Blackfaces like straws and they sought safety by diving into the lake. However, they enjoyed but a brief respite, for the banked up floods which the four whites had so narrowly escaped, also surged northward and temporarily overwhelmed the swimmers.

Collecting their forces, they continued on their way to the scene of the disaster, mouthing in guttural fury to find the way to their intended victims blocked. This setback did not improve the temper of the pursuers. They had set their minds upon a sacrifice with its accompanying horror, the dance of death, and they were not to be lightly turned from their purpose.

Therefore they turned northward again to seek another way to the south, and to the consummation of their revenge upon the fleeing white people. Their great fear was that Oon, whom they knew to be in perfect touch with their doings, would intervene and prevent them from carrying out their intention. If Oon sent his squadrons of Whitefaces to the attack, the Blackface leader realized that his force would be cut off, but such was his determination to destroy the strangers that he was willing to take the risk.

His decision was acted upon immediately, but the wings of the Blackfaces had hardly set them upon their course, when in the far distant Whiteface City the order was given by Oon for the squadrons which the Blackfaces feared so much, to assemble.

Oon's squadrons had already taken wing and arrived at the plateau some time before the Blackfaces. There, taking up strategic positions they awaited the coming of the enemy. Warned by Oon, they knew from which direction their opponents would come, and made preparations for their reception accordingly.

But greater forces were abroad than that of mere physical prowess. Something had been loosed within the darkness against which the efforts of the rank and file of both races could not avail. This was made manifest when the Blackfaces made their appearance.

The arrival of their hereditary enemies on any occasion was usually the signal for the Whitefaces to give battle, but instead of the squadrons throwing themselves immediately into flight, they remained quiescent and waited with intense interest for developments. The Blackfaces also failed to assume a belligerent attitude, but, flying on (although they knew that the Whitefaces were there in force) they alighted on the plateau, assembling in regular battle formation on the cliff edge.

On the completion of this manoeuvre the Whitefaces came from their retreats and formed up in a like manner on the cliff. Then both forces waited expectantly. They had not long to wait. A dark form rose in the air. It was Oon who now hovered over the lake. Presently another flyer took the air. It was the Blackface leader. Tensely both forces watched and waited for the development of the combat which was about to take place, without a flicker of an eyelid.

Presently they saw two black shapes engaged in deadly combat for supremacy. Armed with club and knife, they sought to slay. Circling, diving with lightning speed, each combatant endeavoured to gain an advantage. Oon rose high in the air. His opponent passed him in a lightning dive, his knife slashing at Oon's wing tendon, narrowly missing its objective. As the Blackface passes, Oon rides the upper air, and ere his opponent has time to turn, flashes downward to attack the Blackface as he swings round, and nearly succeeds. His wily enemy evades the swinging stroke of Oon's club by inches. Twisting, turning, the participants in the weird battle use every ruse to disable each other, and at last they meet almost head on.

As Oon swerves, his opponent is seen to flutter wildly. He has been hit; his speed decreases. Oon again soars, turns quickly and dives at his foe. Unable to evade him, the Blackface receives a blow from Oon's club upon his previously injured wing. Unbalanced, he commences to fall. Oon shows no mercy. Again soaring above his enemy he swings his deadly club and crashes it upon the head of the Blackface, splitting it in twain. Crumpling in midair, the lifeless form falls headlong into the lake.

The battle is over—is won. Sensing in the defeat of their champion that the forces arrayed against them are too strong to combat successfully, the Blackfaces accept the inevitable. Taking off from the cliff, they head back toward the Blackface domain.

Oon's squadrons do not attempt to interfere. The Blackfaces are free to make their escape unmolested. Oon's victory has completely demoralized them.

With the disappearance of the Blackfaces, Oon with a majestic sweep circles over his forces then heads towards the Whiteface City, followed by his squadrons.

CHAPTER XXVIII. — LEAD, KINDLY LIGHT

FOR some distance the way lay straight ahead, then the tunnel began to twist and turn confusingly until sense of direction was nearly lost. They entered caverns with seemingly a hundred entrances and exits. They were in a veritable maze, out of which it seemed impossible they would ever find a way. After miles of such travel the labyrinth ended and they entered a cavern apparently limitless in extent. Its roof was not visible, and Ned, investigating, made the discovery that they were on a narrow ledge which extended along the wall on the brink of a yawning cavity. Turning to the right, they traversed the ledge, which was too narrow for them all to walk safely abreast.

After advancing some distance, they had the impression of walking in a circle. Curiously examining the walls as they progressed, Rogers concluded that they were in a hollow mountain, possibly an extinct volcano. Soon the way became more dangerous. The ledge terminated abruptly at a wall, but continued in the form of a causeway from the wall right across the abyss—possibly bottomless, probably hundreds or even thousands of feet deep.

Two could not walk abreast upon the narrow track. They must perforce trust to Rogers who now led the way. Slowly they proceeded. To lose nerve courted destruction. In places the path narrowed to a couple of feet. Sometimes it widened into spaces roughly circular in shape, where the causeway was buttressed by enormous pillars. On one such broad platform Rogers stopped and sat down. All thankfully welcomed the respite, for the negotiation of the causeway to that point had been a nerve- racking experience. As they rested, they were conscious of falling water far below. Possibly it was the stream, which they had followed as far as the tunnel, finding its way to a lower underground level.

Silence reigned but for the tinkling of falling water. The party now took the opportunity to refresh themselves with food and drink. After a space they arose and resumed the passage of the causeway. At last the trying ordeal was over. They had crossed to the other side. The causeway led to an opening in the wall, and continuing onward they found themselves in a series of small caverns linked by passageways. For many hours they kept afoot, until at length they reached a semi-circular chamber to which there was apparently no exit. This, then, was the end of their search. A blank wall faced them!

Consulting his pocket compass, Rogers located a point on the cavern wall bearing south by east. At that point he examined the wall, but beyond discovering a fault which extended across the cavern, he did not find the crack or aperture for which he searched. His eyes could not penetrate far enough into the darkness. Referring to his diary and pocket calendar, he found they had arrived at this dead end on the twenty-first day of December, the longest day.

Calculating that it must be very early morning, he rejoined his companions. They concurred in Rogers' conjecture. But where was the light? Where the great spirit of the Birdmen? They had not found it. All was now so hopeless. They had been following a shadow. Tired, dispirited, the three gazed into each other's eyes. As they sat thus, sleep overtook them.

When they awakened, they dispiritedly partook of food. Rogers' face had become lined. Anxiously he consulted his watch; a few more minutes would decide their fate. Thus they waited with beating hearts for the verdict—life or death?

Suddenly a gleam of light stabbed the darkness. The light broadened, increasing in intensity each moment. Overpoweringly came the realization that their dream had come true! Their hopes had been realized. They were in the Cavern of the Great Spirit— the Mecca of the Birdmen who many years before had come annually to worship!

With a shout of joy they sprang to their feet. No time was to be lost if this, the consummation of their great endeavour, was to aid them in regaining their liberty. Judith, shaken with emotion, flung herself on Rogers' breast and sobbed out her joy.

Their first care while the light remained was to make a thorough search of the cavern. Presently they found the aperture through which the fault or crack continued right across the cavern. By clearing away the loose sand they traced its erratic track until it reached the opposite wall. To their delight the crack extended up that wall also.

Locating the most likely spots for penetration, the drill and sledge hammer were brought into requisition. The crack was enlarged sufficiently to allow charges of explosives to be placed in position. Luckily the light lasted long enough for them to complete their preparations. The charges were fixed and the fuses attached. All that remained was to put their luck to the test; what the result would be they could not estimate. To avoid injury from the explosion they must choose positions sufficiently far back to be out of danger, but where the safety line was they could not gauge even approximately.

"Well, boys, and Judith," Rogers said impressively when they had completed their work, "it is the last throw of the dice, and it is of no use delaying putting our fate to the test."

Four charges had been fixed containing the whole of their explosives, and ample length of fuse attached to enable them to get well out of reach of falling rock. In order that the explosions would take place simultaneously, each stood by with match in hand ready to light the fuse at a given signal.

"Fires on!" called Rogers, and four fuses began to splutter. Immediately they ran to a place of safety to await the explosion. The seconds dragged like hours. When the gelignite exploded would they still be confined within the grim walls of the cavern, or, they wondered, would God's sunshine stream in to light their dungeon?

The silence became oppressive. They could hear their hearts beating. Their temples throbbed under the tension. Would it never come? Doubts began to assail them. Perhaps the fuses had failed. But it was hardly possible for four fuses to fail, they reasoned.

The exclamation was not blasphemous. It was a cry to the Almighty for protection which sprang involuntarily from their hearts and lips. The world surely was shattered, torn asunder! The rock floor trembled violently. A deafening medley of sound pounded at their ear-drums. Gradually the turmoil ceased, the echoes died. Anxiously they turned towards the place of explosion. What would they find? So much depended upon the result. Was it to be open air and freedom, or to be condemned to end their days away from their loved ones? Virtually buried alive. Eagerly they pressed forward and noticed a distinct change in the atmosphere. A current of air caressed their flushed faces. Hope arose in their hearts. A few more steps, then they saw curling smoke.

Light! Wonderful light! They fell on their knees to thank Him who had watched over them for His mercy. Then covered their eyes, for they could not bear to look upon the brilliant sunshine which streamed into the cavern. Deliverance had come to them. They were content to wait until they could gaze without discomfort at the glorious panorama which they sensed lay before them.

It was some time before their eyes became accustomed to the light, and then they perceived the effect of the explosion. The cavern had been cut in twain as if by a knife. Before them lay a great gorge surrounded by precipitous cliffs. They were facing south-east and a rising sun was turning the mists into billows of silver.

Below, clouds of dust lingered, and the debris from the fallen mountain could be discerned piled far out into the gorge. From the mouth of the cavern to the nearest mass of piled-up debris was a drop of a hundred feet; to the bottom was probably another thousand yards.

After a cursory glance at the wonderful vista spread before them, they turned appraising eyes on each other. The once healthily tanned faces of the men had assumed a pallor which shocked them. Judith's skin was quite transparent. Their appearance among men would have caused instant comment. During their incarceration, Rogers, Ned and Jim had kept themselves shaven and, beyond their deadly pallor, they had not changed much in appearance. They were thinner perhaps, but still vitally healthy. Even now the terrible experience of the past months was being relegated to the dim past.

Judith with a full heart thought of home. She, whom they thought to be dead, would return. The girl pictured the joy of the meeting and the happiness that would ensue by the return of Ned, Jim and Rogers. It was all too wonderful to think about; too good to be true. Perhaps it was only a dream after all. Judith had never really met the three men in the caverns. She would awaken to find eternal darkness still surrounding her, with the dark figures of the Whiteface inhabitants flitting to and fro.

A hand laid gently upon her shoulder recalled her to realization that it was not a dream. It was Rogers.

The way to freedom had been opened, but their position was still precarious. Rocks were still crashing into the valley. Clouds of dust and earth poured ominously from the face of the mountain. Possibly the fall which had taken place was but the forerunner of greater destruction. It was not safe to linger too long in the vicinity.

Judith was first lowered down the cliff, Ned and Jim followed quickly. Next came their precious wireless. Rogers was the last to leave the cavern. Their way lay among immense boulders, and often the rope had to be brought into requisition to enable them to negotiate the obstacles. Luckily they were travelling down- hill, and they proceeded without undue fatigue.

The tremendous rock fall had filled up a deep gorge, enabling them to cross to the other side of the valley. There they made camp at a safe distance from the crumbling mountain and rested.

The cavern was still in plain view, and, as they gazed upon the black and sinister opening far up in the face of the cliff, their thoughts traversed once again the path of thrilling adventure which they had trod.

Rogers shuddered in realization that a way of egress from the caverns to the outside world was now open to the Birdmen. Had not their own lives depended upon it he would wish that the way had never opened.

In apparent answer to his apprehensive thought came a heavy rumbling, then with ear-splitting concussions boulders began to plunge down the mountain side. Cliffs crumbled. Amid unearthly cataclysmic uproar the entire mountain collapsed and the cavern from which they had emerged, disappeared.

Rogers gave a sigh of relief. The way of escape which had opened to them for a few hours had closed again for ever.

Far back in the Whiteface City, Oon knew that his friends had found the Great White Spirit, but his own eyes still looked upon eternal darkness as he had foretold.

CHAPTER XXIX. — GOOD NEWS

MEL waited patiently for another message from the caverns. Day after day, since Rogers had transmitted an account of their adventures in the haunt of the Serpent, Mel had stood by, but the set had remained silent. She refused to believe that all was not well. Perhaps their batteries had given out, she reasoned. If such were the case she could not hope to hear Rogers' well-known signal.

As she sat thoughtfully regarding the instrument her mother entered her little den.

"Do not worry, Mel," her mother said, smiling cheerfully, but the look of anxiety in her eyes could not be concealed. Her heart was heavy with fear for her loved ones, but like Mel, she did not willingly allow her anxiety to become manifest.

"They will soon be with us again. I have every confidence in Major Rogers. He has already proved his ability to get out of tight corners, and both Ned and Jim can be relied upon in case of emergency."

Mel looked at her mother gratefully. Then Mrs. Grattan touched her daughter's curly head with her lips.

After her mother had left the room, Mel sat trying to visualize the interior of the caverns. Suddenly a musical tinkle came from the set, and Mel, trembling with suppressed excitement, recognized Rogers' familiar call. She waited tensely, then the set came to life.

Mel tapped out the answering call. "M.E.L. listening. Carry on R.G.S." then, pencil in hand, she waited for Rogers' communication.

For twenty minutes Mel decoded Rogers' message. As she listened and wrote, tears dimmed her eyes, but they were tears of joy. Mel could hardly believe the words she had written. Rogers, Ned and Jim were safe, and they had found Judith. It took all of Mel's will power to prevent her running to her mother with the wonderful news before Rogers had finished. It was almost unbelievable that they had really escaped and that Judith had been found.

When the last tap had sounded Mel sprang to her feet. Pad in hand, she burst in upon her startled parents.

"Oh, Mum and Dad," she gasped. "They have escaped." Overcome by emotion, Mel sank to her mother's feet and buried her face in the latter's lap. The elder people looked at one another and a shadow seemed to have passed from their faces. Tenderly placing her arm around the shoulders of the sobbing girl, in a gentle voice Mrs. Grattan said:

"Oh! Mother, they have really escaped," she said, "and have found someone whom we thought to be dead."

"Who, Mel?" asked Mrs. Grattan in astonishment. Then Mel gently breathed the name:

If a bombshell had exploded it could not have startled her parents as much as Mel's announcement. Incredible they thought. Judith had disappeared over three long years ago. Mel looked at her parents' perplexed faces.

"It is quite true, Mummie and Dad. Let me read the message, although I can hardly believe it."

ROGERS' MESSAGE.

"We have at last been fortunate enough to escape from the caverns and find God's sunlight good. We are in good health and have a pleasant surprise for you, Mel. We have added another member to our party—someone we lost sight of nearly three years ago. It is astonishing how we meet people in the most unexpected places. We have found Judith Blaircourt. Judith had contrived to let herself get down in a whirlpool in Blaircourt Lake, but arrived safe and sound in the caverns below.

"However, Judith was always able to adapt herself to circumstances, and made herself as much at home as her new environment would permit; in fact, she attained an exalted position among the inhabitants of the caverns, for on our arrival, Judith was introduced to us as the Birdman Queen. Well, Queen or not, she was still Judith enough to do a little weep on Uncle Jack's shoulder when we were introduced. So there you have it, Mel. By good fortune we found Judith in a most unexpected manner. She has grown to be a lovely woman, just like you. Get some frocks ready for her. She needs some badly.

"Now, Mel, I have broken the good news as gently as I could. I want you to do the same to her mother. It will be difficult, Mel, but I will leave it to you.

"You must go to 'Blaircourt,' wait for an opportunity when her mother mentions Judith's name, then invent any little fiction you think will arouse the spark of hope for her return.

"If that spark is seen, fan it with your woman's wit and God prosper your efforts. Do not announce Judith's return to any other than your father and mother until she has been placed in her own mother's arms.

"We are camped in a densely-wooded gorge overlooked by mountains—one in particular scarred by recent rockfalls. It does not seem possible to escape from the gorge by our own efforts, therefore it will be necessary to enlist the services of a helicopter and pilot. There is no suitable landing place for an ordinary machine. Whatever lands here will have to drop down almost perpendicularly. See Colonel R. at his office. He will make the machine available at once. Ask him to keep our escape secret until Judith's mother has been warned of her safety. Send provisions, clothing and tobacco, also a small tent for Judith's use. We possibly may have to stay here for a few days after the helicopter's arrival. We will look for a suitable landing place and send up smoke signals for the guidance of the pilot.

"Our position is approximately 100 miles due south of 'Blaircourt.' Advise pilots to circle over the country when reaching this position. Batteries are showing signs of going flat. Advise planes equip with radio detector. I will send signals if we sight planes whilst batteries last.

When Mel had finished, Captain Grattan immediately phoned Colonel R. When the Colonel had grasped the purport of the communication, his satisfaction was evidenced by his first remark.

"Gad, Grattan, that is good news. I do not anticipate any difficulty in finding them. Three planes will leave in the morning to make a search. When they have located the party, the helicopter will be sent to pick them up. I will see you to-night to discuss details."

"There you are, Mel." Captain Grattan turned to his daughter. "Three planes will start in the morning and the helicopter will stand by to pick them up when they have been located.

"The Colonel is coming to visit us to-night, and as you have to go to 'Blaircourt' to break the news to Judith's mother, I will arrange for you to fly there in one of the planes. They will be passing over 'Blaircourt' and will land you at the nearest aerodrome. A car will be waiting to take you to your destination."

Mel's heart was light as she made preparation for her visit to "Blaircourt," and thrilled with pleasure as she packed articles necessary for Judith's use. She visualized Judith regarding herself in a mirror for the first time in three long years, and her sensations when the little comforts so long denied were actually available.

Mrs. Grattan had turned her attention to the wants of the three men, and soon had the necessary articles packed. If the stranded wayfarers could have seen the contents of the hamper Mrs. Grattan packed for their use they would have imagined it was only a dream.

Mel went to sleep that night happy. Colonel R. had been wonderful. Nothing had been left undone that would help to make a speedy rescue possible. He had readily agreed to the proposal that one of the planes should take her to "Blaircourt" and be available whenever she should wish to return.

Mel had also extracted a promise of another favour which the Colonel, after some demur, granted, provided she could get her father and mother to consent.

"All right!" exclaimed the Colonel. "If that is the case then it is as good as accomplished."

What Mel's favour was we must leave to another chapter and to the reader's imagination.

CHAPTER XXX. — MEL VISITS "BLAIRCOURT"

EARLY next morning Mel motored to the aerodrome where the three planes were waiting to start. As soon as she was safely aboard the planes took off. They rose gracefully and after circling the aerodrome took a course westward.

Mel was quite familiar with flying. On more than one occasion she had been allowed to take control and proved that she possessed many qualities essential to a successful flyer.

She had flown to "Blaircourt" before, but never on a mission so delicate as that which was now taking her westward. She would require consummate tact to bring to a happy conclusion the task before her.

With a heart slightly weakened by the supposed death of Judith, infinite care would be necessary to break the news of Judith's survival to her mother.

The flight proved to be uneventful and the plane landed Mel at an aerodrome a few miles distant from "Blaircourt." Mel lingered and watched the plane take off again to join its consorts. As they straightened and headed south Mel breathed a heartfelt prayer for the success of their undertaking.

Mrs. Blaircourt, who had been advised of Mel's coming, gave her a motherly welcome. Since the loss of Judith she had taken Mel to her heart and had found consolation in having her near, and Mel had been more than glad to be the means of giving some little measures of comfort to the stricken mother.

They sat together on the cool verandah overlooking the valley where once the lake had been. Mel had not before seen the result of the earth tremor which had shaken the foundations of the Blaircourt's home, and resulted in the disappearance of the lake.

The scene before her was one of grandeur and desolation. Where once the lake shimmered in the sunlight, masses of great rocks were now visible. Mel did not yet know that the tremor which had shattered the great cliffs overlooking the far side of the lake had been the means of saving the entombed people in the caverns from the vengeance of the Blackfaces.

As the waters of the lake deluged the caverns below the cliffs fell bodily and completely filled the cavity left by the waters, sealing for all time the mouth of the Debbil-Debbil that had swallowed the Big King Fellow centuries ago, and later, Judith.

Providence that had shaped those cliffs had sent them crashing down at the psychological moment when four helpless humans had the greatest need for miraculous intervention.

Mel did not know this, or she would have greeted as friends the great boulders now filling the old lake bed.

"I was thinking of my brother and of the boys, Mel. Have you had any further news from them?"

"Yes," answered Mel slowly. "We had a message from them yesterday afternoon; they are all well and have great hopes of soon getting out of the caverns."

"Just like Jack," smiled Mrs. Blaircourt. "He was always an optimist. He had hopes even that my Judith would eventually be returned to me, and sometimes I feel that she will return some day."

"I am glad you said that, Auntie, for I have the same feeling myself. I have been thinking very much about Judith recently and I have had some strange fancies regarding the cause of her disappearance, and I think that I have solved the mystery. May I talk freely, Auntie?"

"Yes, dear," was the answer. "Up till now I have tried to avoid thinking too much about Judith, but I seem to feel different about it to-day. It is different somehow."

Mel resumed. "You remember the old aborigine legend about the Debbil-Debbil who swallowed the Big King Fellow and his canoe, the Debbil-Debbil of Blaircourt Lake? Well, this is what really happened. Centuries ago the Black King and his canoe were drawn down by a whirlpool which formed in the deepest part of the lake- -a whirlpool caused by portions of the lake bed breaking away. Having been drawn down, he was carried to the caverns below. By some means the Black King made his escape, and later made a map of the caverns through which he had passed. That map, or token, was entrusted to Major Rogers by an old aborigine friend, Bal- yari, who warned him that it would lead him to dangerous places. Bal-yari also warned him that the mountains would shake. Your brother ignored the warning and went exploring, taking with him Ned and Jim. You know how they were cut off by the caving in of the mountain.

"Now," resumed Mel, "if the Black King after being drawn down by the whirlpool could escape, it is quite possible for another person to have had a similar experience."

"Do you," she said haltingly, "do you think that Judith, too, was drawn down by the whirlpool?" Mel nodded gravely. "I do think so, and I also think that like the black man, she has escaped."

Mel looked uncomfortable, for she had a very vivid spasm of self-analysis. Mel, you little cat, you are simply horrid, and half a little liar as well. Oh, what will she think of me when she learns that I knew Judith was alive and well all the time I was windbagging about the old nigger and his canoe. Pull yourself together, you unfeeling little toad. You have to go on with it.

Mel replied that it was not only possible but probable, that it had happened that way.

Mrs. Blaircourt's interest had been aroused by Mel's masterly effort. She found herself reasoning that Judith must have been drawn down by the whirlpool and confined in the caverns. Was it not possible that her brother might find her and bring her back? Carried away by the thought, she sighed. Oh, if they could only find her. Then she felt a pair of soft arms creep around her neck, and then, cheek to cheek, Mel whispered:

"I wanted so much to tell you before, dear. They have found her. Judith is coming back to you, and so is your brother with Ned and Jim."

For a long time they remained in each other's arms as Mel told her story. Then the elder woman, convinced and happy, murmured:

During the evening a long-distance call put through by Mel gave her parents the glad tidings that Mrs. Blaircourt was now aware of Judith's safety. Mel's qualms of conscience were appeased and she went to bed with the conviction that as a diplomat and bearer of good tidings she had been quite a success.

CHAPTER XXXI. — SMOKE SIGNALS

AS they stood and watched the awe-inspiring spectacle of the crumbling mountain, they took little heed of the trembling of the ground underfoot, or of an intermittent bombardment of the valley by rocks dislodged by the tremor from the cliffs surrounding them. Occasionally a tree, perched precariously upon a ledge, would fall, heralded by an ominous crackling sound as its roots were torn asunder, then the roar of an avalanche of debris which followed its headlong fall to the gorge below.

When at length the last echoes of the convulsion had subsided they viewed their surroundings. They were in a deep gorge hemmed in by precipitous cliffs, which not even a mountain goat would attempt to climb. The slope from the cliffs to the small river which flowed over a rocky bed down the centre of the gorge, was covered by giant gums, and the shade cast by their closely interwoven branches proved grateful to their tired eyes, strained by the glare of the unaccustomed sunlight.

Their first care was to find a suitable camping ground. An overhanging ledge was soon located, and under it they placed their few remaining belongings. As they had not partaken of food for many hours, a fire was lit and a scanty repast made upon the remainder of the smoked fish brought from the caverns.

Rogers was not perturbed about their future food requirements. His knowledge of bushcraft would enable him to provide them with sufficient until help arrived.

After they had satisfied their hunger Rogers busied himself with getting the wireless in order. He found that the batteries, which had been charged before leaving the Birdman City, were still strong enough to enable him to send at least one long message.

The boys and Judith stood by, anxiously awaiting the result of Rogers' attempt to get in touch with Mel. Presently the signal came that Mel was listening in. Rogers sent his message, and then a final call from Mel assured them that she had received and fully understood his communication.

"That is splendid," commented Rogers. "We must now see if there is a suitable place for the helicopter to land. There may be some open space, visible from the air, upon which a landing could be made. If we find one we will send up our smoke signals from it."

Picking their way through the undergrowth, they started to explore up-stream. It was rough walking, and the remnants of sandshoes which still clung to their feet were very little protection against the rocks upon which they were forced to travel.

As they proceeded the gorge widened and presently they came to a clearing about half-an-acre in extent; the surface of which was entirely composed of rock covered with a thin layer of moss and leaves. The clearing was surrounded by giant gums, excepting on the side overlooking the river, and formed a natural amphitheatre. The rock overhung a clear pool in which fish could be seen swimming lazily over the rocky bottom. There was a food supply close at hand.

"I have no objection to fish as an occasional diet, but our Friday has lasted for ten months. What I want is a solid piece of steak and onions."

"Ned, I am ashamed of you," mocked Jim, with a wink at Rogers, "when a man wants steak and onions, he can't be."

Ned blushed so furiously that his pallor disappeared as if by magic, whilst Judith turned away hurriedly and pretended to be interested in a cicada that had landed on a near-by twig. Rogers' eyes twinkled. Jim was getting back into his old form again.

Having found a suitable landing place, they returned to the camp and set about preparing for their first nigh in the bush. A bed of ferns and leaves was indeed a luxury after their recent experiences. Stretched at ease, with a glowing fire at their feet, they discussed the chances of their whereabouts being discovered by the search party.

"We will have to rely upon our smoke signals," Rogers affirmed. "Luckily, we have a blanket."

"What do you want a blanket for?" asked Judith, to whom the making of smoke puffs was a mystery. Ned and Jim, however, were quite familiar with the operation.

"With a blanket," explained Rogers for Judith's benefit, "or any other covering, the smoke made by burning green stuff is confined until sufficient has collected to make a small cloud when released. If the day is calm the puff ball of smoke will rise without dispersing. The puffs sent into the sky at intervals by the natives are read as easily as our own Morse code. On a clear day they can be seen for miles, and an aeroplane would have no difficulty in tracing them to within measurable distance of their source. If the day is windy we will build a big green fire and send as much smoke out of the gorge as we can, and if the plane appears in sight I will, if necessary, supplement our smoke signals with Morse until the batteries give out."

Out from the shadow of the trees hopped a rock wallaby; pausing, the creature blinked at the fire, then gazed curiously at the recumbent forms. Satisfied with his inspection, he hopped off sedately on his way to the water.

"That little fellow seemed to be quite self-possessed," remarked Judith. "He was not at all afraid of us. I have noticed also that birds here are quite friendly. One perched on my shoulder when we were at the clearing. I suppose nobody has ever been here to frighten them."

"Not even natives," agreed Rogers. "I do not think that humans have ever set foot in this place before."

Rogers rose and replenished the fire, then again he sought his bed of leaves, to fall asleep marvelling at the ways of Providence which had at last brought them by devious paths from the labyrinth of the caverns to the comparative safety of the gorge.

Refreshed by a good night's sleep, they awoke as dawn was breaking. In the branches of the gums above, with much screeching and argument a flock of cockatoos discussed the programme for the new day. They evidently had a somewhat sceptical audience listening to their family conclave, for the proceedings had to be frequently abandoned in order to allow the audience—an inquisitive band of kookaburras—to indulge in a hearty burst of derisive laughter.

Ned's quip at Jim's expense reminded Rogers of the day they had entered the cave in the crater, when the dawn was ushered in by such another chorus.

Jim responded by an ostentatious display of his fishing line as he sauntered off to the pool in search of breakfast. Jim fished whilst the rest of the party collected firewood. He was successful in landing a number of small mountain trout, of which there seemed to be an endless supply in the pool. Upon these they breakfasted, then turned their attention to the making of the smoke signals.

Rogers judged that the plane would set out at dawn, and if it started from the aerodrome near "Blaircourt," it could not now be far from the vicinity of the gorge. The fire used for cooking their breakfast of fish was fed with green boughs and bark stripped from near-by trees, and was soon smoking densely.

The blanket was now requisitioned and spread over the fire. A green stake, kept upright between two stones, prevented the blanket from contact with the flames. They held the corners well down until Rogers gave the signal for the blanket to be drawn aside. Then up went the first puff ball into the blue sky overhead.

They worked zealously, sending up signals at intervals, varying the procedure by discarding the blanket and allowing the smoke to ascend in a thin column.

It was three hours after dawn when they heard the drone of a plane. Soon the machine was circling overhead. Apparently its occupants had located their position, then for a time it disappeared coming into view again about a mile up-stream. Another puff-ball was released; banking, the plane turned and headed straight down the gorge, following the course of the stream. It passed just overhead, and as it did so the anxious watchers saw a hand wave, and a small parachute came sailing downwards, landing a few moments later on the edge of the clearing. The plane, after dropping the parachute, rose and continued to circle over the gorge. Meanwhile Rogers had opened the package and found a hastily-scribbled note from the plane's observer. The message read:

"Send up one smoke signal if take-off conditions are favourable. If not, send two. Helicopter requires at least thirty feet run to take off again safely. Is surface smooth? It can land easily. The takeoff is most important. If all O.K. expect helicopter in about two hours. Will wireless it to start on receipt of your affirmative signal. Will meet helicopter and escort it here and stand by when making landing. Be ready to leave immediately. Cheerio. Harford. Observer."

No time was lost in replying to the observer's inquiry regarding the suitability of the landing-place. A signal puff- ball was sent soaring skyward. Observing it, the plane immediately banked again and headed towards them. Another parachute was released as it passed, then the plane, gaining altitude, vanished from sight. The second message dropped was brief:

"Your O.K. signal noted. Confident no difficulty in picking you up. Again cheerio. Harford."

"Quick work," remarked Rogers, as he finished reading. "We can thank our lucky stars that there is such a machine as the helicopter in existence. Also for this open space. A helicopter can land almost anywhere it can find wing and wheel space, but unless it has room enough for a short run it cannot rise, as its lifting apparatus is not an independent unit. The lifting force is supplied by the air stream from the propeller, therefore a short run is necessary and unavoidable. The pilot, as soon as the machine starts forward, gives the engine the gun or full throttle, obtaining the maximum pulling and lifting power as quickly as possible. We will have to manhandle the machine when it lands, and turn it so that it faces the open. Luckily there is plenty of space available. I expect the pilot will keep the engine running until we are ready to move. He is not likely to take a chance down here with a cold engine."

Noon found them still awaiting the appearance of the helicopter. Jim had provided another fish banquet, and to Ned's intense disgust promised that if the helicopter did not arrive they would have fish again for tea. However, Jim's kindly intentions were not to bear fruit, for shortly a distant drone was heard and presently three planes and the helicopter came into view.

After manoeuvring over their position for some time, whilst the three planes circled higher, the helicopter descended into the gorge, passing over the clearing just clear of the tree tops. As if satisfied with his inspection, the pilot turned to make the landing. Coming in from the river side, the machine descended quickly and came to rest on the moss-covered rock as gracefully and lightly as a bird.

As the machine came to rest the pilot stepped down, and opening the cabin door, to the astonishment of the four watchers, gave his hand to a young lady to assist her to descend. One look at her face was enough to send at least three of them almost crazy with delight. In unison they shouted "Mel!" and rushed to meet her. What a welcome. She was gathered up in Ned's embrace, tossed to Jim, then to Rogers, and finally she found herself with Judith's arms around her. Breathless and happy, the consummation of Mel's dearest hope had been achieved, to be allowed to go in the helicopter to meet them. It was for this happy moment that she had used her powers of persuasion on Colonel R.

In the excitement the pilot, for a moment, was forgotten. Approaching Rogers, he saluted; returning the salute, Rogers held out his hand which the other grasped warmly. In turn he was introduced to Judith, Ned and Jim, his hearty handshake marking his pleasure at the meeting. Formalities completed, he turned once more to Rogers.

"My orders, sir, are to take off immediately." Rogers, with a return to his old military manner, replied.

Four willing workers made light of the task of placing the helicopter in position to take-off. The pilot expressed his satisfaction at the space available and the smoothness of the ground. The engine had been left running, as Rogers had predicted, and was now ready to take off. The pilot made a last inspection of his charge, then signalled his passengers to take their seats in the cabin. Mounting to the cockpit, he called:

The motor then awoke the echoes with the thunderous roar of its exhaust. They were leaving the gorge behind them. Soon they would see the faces of the friends who had mourned for them as lost.

CHAPTER XXXII. — HOME

THE scene at "Blaircourt" was a brilliant one, for many old friends had come to welcome back the wanderers from the caverns. At the aerodrome that afternoon, the scene had been a memorable one. The arrival of the escorting planes and the landing of the helicopter was the occasion of a remarkable demonstration. Many thousands had gathered to take part in the welcome. Pressmen and photographers were busy recording incidents of the landing, and as Judith was seen a tumultuous cheer greeted her. Three years in the darkness. Could this be the girl who had faced alone that terrible ordeal? All were anxious to see the brave girl who had with undaunted courage faced the terrors of the caverns and had come through unscathed. No less interest was manifested in Rogers and the two boys, who with difficulty made their way to the car which was to take them to "Blaircourt."

At last they were among their friends. The meeting between Judith and her mother was too sacred for prying eyes to witness; they were still together and still wondering if it were not all a dream.

Ned had met his mother and father, and with Jim had received a welcome such as only parents who had nearly despaired of ever seeing them again, could give.

Mel was everywhere, for Mel was hostess on the great occasion, and as a hostess was quite as successful—as Rogers remarked—as a wireless expert. Rogers, shaved and dressed, had become the Rogers of old.

A toast had just been honoured. There were few who raised their glasses who did not feel a contraction of the throat when they uttered the simple words:

The token and the casket, together with the wonderful pearls brought back from the caverns, were of intense interest to the assembled guests. A handsome pearl had been presented by Judith to each of the pilots of the search planes and helicopter.

Rogers, although just returned from a hazardous journey, was officially still in harness, and this fact was to be brought forcibly home to him. He was dancing with Mel when a message came to say he was required at the telephone. Mel readily granted him the necessary permission to leave her. Escorting her to a seat, Rogers left the room. When he returned he sought Ned and Jim. Taking them aside, he was about to speak when Mel joined the group.

"Come, Mel," he said. "We can have no secrets from you; besides I may require your services also. I have just received an important message from headquarters."

"I want two assistants I can trust, and my choice has fallen upon you. I have orders to prepare at once to proceed to a secret destination on the Queensland coast, to fit out, arm and man a fast motor vessel to search for 'The Mysterious Sampan'."

The caverns were forgotten as the pair clasped Rogers' hands sealing the compact. Their thoughts had already taken wing to alluring scenes of fresh adventures.

T.E. GRATTAN-SMITH

THE CAVE OF A THOUSAND COLUMNS

ADVERTISEMENT FOR "THE CAVE OF A THOUSAND COLUMNS"
PUBLISHED IN THE AGE, MELBOURNE, AUSTRALIA, 27 JULY 1935

TABLE OF CONTENTS

LIST OF ILLUSTRATIONS

CHAPTER I. — THE CAVE IN THE CRATER

CHAPTER II. — A DAY OF TOIL

CHAPTER III. — A MESSAGE TO MEL

CHAPTER IV. — ROGERS EXPLORES THE CAVERN

CHAPTER V. — A GRAVE DECISION

CHAPTER VI. — MEL RECEIVES BAD NEWS

CHAPTER VII. — RIGHT TO THE END

CHAPTER VIII. — FACING THE UNKNOWN

CHAPTER IX. — THE CAVE OF A THOUSAND COLUMNS

CHAPTER X. — THE TOKEN

CHAPTER XI. — THE RUSTLE OF WINGS

CHAPTER XII. — ON GUARD

CHAPTER XIII. — WATERS OF DEATH

CHAPTER XIV. — THE DEVIL'S MAW

CHAPTER XV. — CANNIBALS OF THE CAVERNS

CHAPTER XVI. — A FIGHT FOR LIFE

CHAPTER XVII. — THE DEATH PIT

CHAPTER XVIII. — A MYSTERY SOLVED

CHAPTER XIX. — JUDITH BLAIRCOURT'S STORY

CHAPTER XX. — THE BLACKFACES GIVE BATTLE

CHAPTER XXI. — TWO FIGHTS TO A FINISH

CHAPTER XXII. — THE SPIRIT OF THE CAVERNS

CHAPTER XXII. — THE HAUNT OF THE SERPENT

CHAPTER XXIV. — LOOKING BACKWARD AND THE CAVE OF PEARLS

CHAPTER XXV. — MER

CHAPTER XXVI. — PURSUIT

CHAPTER XXVII. — BAULKED

CHAPTER XXVIII. — LEAD, KINDLY LIGHT

CHAPTER XXIX. — GOOD NEWS

ROGERS' MESSAGE.

CHAPTER XXX. — MEL VISITS "BLAIRCOURT"

CHAPTER XXXI. — SMOKE SIGNALS

CHAPTER XXXII. — HOME

THE END

T.E. GRATTAN-SMITH

THE CAVE OF A THOUSAND COLUMNS

ADVERTISEMENT FOR "THE CAVE OF A THOUSAND COLUMNS" PUBLISHED IN THE AGE, MELBOURNE, AUSTRALIA, 27 JULY 1935

TABLE OF CONTENTS

LIST OF ILLUSTRATIONS

ROGERS' MESSAGE.

THE END

ADVERTISEMENT FOR "THE CAVE OF A THOUSAND COLUMNS"
PUBLISHED IN THE AGE, MELBOURNE, AUSTRALIA, 27 JULY 1935