But the night was considerably older ere any one of that quartette lost himself in slumber, for all had been too thoroughly wrought up by the exciting events of the past day for sleep to claim an easy subject.

By common consent, however, that one particular subject was barred for the present, and then, sitting in a cosy group about the glowing fire there in the cavern, the recently formed friends talked and chatted, asking and answering questions almost past counting.

Little wonder that such should be the case, so far as Cooper Edgecombe was concerned, since he had been lost to the busy world and its many changes for a long decade.

Then, too, his own dreary existence held a strange charm for the air-voyagers, and the exile grew wonderfully cheerful and bright-eyed as he in part depicted his struggles to sustain life against such heavy odds, and still strove to keep alive that one hope,—that even yet he might be able to discover a clew to his loved and lost ones.

“Not alive; I have long since abandoned that faint hope. But if I might only find something to make sure, something that I could pray over, then bury where my heart could hover above—”

“You are still alive, good friend, yet you have spent long years out here in the wilderness,” gently suggested the professor.

Edgecombe flinched, as one might when a rude hand touches a still raw wound.

“But they, my wife, my baby girl,—they could never have lived as I have existed. They surely must have perished; if not at once, then when the first cruel storms of hideous winter came howling down from the far north!”

“Unless they were found and rescued by—who knows, my good sir?” forcing a cheerful smile, which, unfortunately, was only surface-born, as the exile lifted his head with a start and a gasping ejaculation. “Since it seems fairly well proven that this supposedly unknown land is actually inhabited, why may your loved ones not have been rescued?”

“The Indians? You mean by the Aztecs, sir?”

“If Aztecans they should really prove; why not?”

“But, surely I have heard—sacrifices?” huskily breathed the greatly agitated man, while the professor, realising how he was making a bad matter worse, brazenly falsified the records, declaring that no human sacrifices had ever stained the record of that noble, honourable, gallant race; and then changed the subject as quickly as might be.

Nevertheless, there was one good effect following that talk. Cooper Edgecombe had dreaded nothing so much as the fear of being left behind by these, the first white people he had seen for what seemed more than an ordinary lifetime; but now, when the professor hinted at a longing to take a spin through ether, for the purpose of winning a wider view, he eagerly seconded that idea, even while realising that it would be difficult to take him along with the rest.

Still, nothing was definitely settled that evening, and at a fairly respectable hour before the turn of night, the air-voyagers were wrapped in their blankets and soundly slumbering.

Not so the exile. Sleep was far from his brain, and while he really knew that danger could hardly menace that wondrous bit of ingenious mechanism, he watched it throughout that long night, ready to risk his own life in its defence should the occasion arise.

Why not, since his whole future depended upon the aeromotor? By its aid he hoped to reach civilization once more; and in spite of the great loss which had wrecked his life, he was thrilled to the centre by that glorious prospect. Here he was dead while breathing; there he would at least be in touch with his fellow men once more!

An early meal was prepared by the exile, and in readiness when his trio of guests awakened to the new day; and then, while busily discussing the really appetising viands placed before them, the next move was fully determined upon.

Not a little to his secret delight, the professor heard Edgecombe broach the subject of further explorations, and seeing that his excitement had passed away in goodly measure during the silent watches of the night, he talked with greater freedom.

“Of course we'll keep in touch with you, here, friend, and take no decisive move without your knowledge and consent. Our fate shall be yours, and your fate shall be ours. Only—I would dearly love to catch a glimpse of—If there should actually be a Lost City in existence!”

“If there is, as there surely must be one of some description, judging from the number of red men I have seen collecting here at the lake,” observed the exile, “you certainly ought to make the discovery with the aid of your air-ship. You can ascend at will, of course, sir?”

Nothing loath, the professor spoke of his pet and its wondrous capabilities, and then all hands left the cavern for the outer air, to prepare for action.

As a further assurance, uncle Phaeton begged Edgecombe to enter the aerostat, then skilfully caused the vessel to float upward into clear space, sailing out over the lake even to the whirlpool itself before turning, his passenger eagerly watching every move and touch of hand, asking questions which proved him both shrewd and ingenious, from a mechanical point of view.

Returning to their starting-point, Edgecombe sprang lightly to earth to make way for the brothers, face ruddy and eyes aglow as he again begged them all to keep watch for aught which might solve the mystery yet surrounding the fate of his loved ones.

The promise was given, together with an earnest assurance that they would soon return; then the parting was cut as short as might be, all feeling that such a course was wisest and kindest, after all.

For an hour or more the air-ship sped on, high in air, its inmates viewing the various and varying landmarks beneath and beyond them, all marvelling at the fact that such an immense scope of country should for so long be left in its native virginity, especially where all are so land-hungry.

Then, as nothing of especial interest was brought to their notice, uncle Phaeton quite naturally reverted to that suit of Aztecan armour, and the glorious possibilities which the words of the exile had opened up to them as explorers.

Bruno listened with unfeigned interest, but not so his more mercurial brother, who took advantage of an opening left by the professor, to bluntly interject:

“What mighty good, even if you should find it all, uncle Phaeton? You couldn't pick it up and tote it away, to start a dime museum with. And, as for my part,—I'll tell you what! If we could only find something like Aladdin's cave, now!”

“Growing miserly in your old age, are you, lad?” mocked his uncle.

“No; I don't mean just that. His trees were hung with riches, but mine should be—crammed and crowded full of plum pudding, fruit cake, angel food, mince pies, and the like! Yes, and there should be fountains of lemonade! And mountains of ice-cream! And sandbars of caramels, and chocolate drops, and trilbies, and—well, now, what's the matter with you fellows, anyway?”

He spoke with boyish indignation at that laughing outbreak, but the kindly professor quickly managed to smooth the matter over, although not before Waldo had promised Bruno a sound thumping the first time they set foot upon land.

Until past the noon hour that pleasant voyage lasted, without any remarkable discovery being made, the trio munching a cold lunch at their ease, rather than take the trouble to effect a landing.

But then, not very long after the sun had begun his downward course, there came a change which caused Featherwit's blood to leap through his veins far more rapidly than usual, for yonder, still a number of miles away, there was gradually opening to view a hill-surrounded valley of considerable dimension, certain portions of which betrayed signs of cultivation, or at least of vegetation different from aught the explorers had as yet come across since entering that land of wonders.

Almost unwittingly Professor Featherwit sent the air-ship higher, even as it sped onward at quickened pace, his face as pale as his eyes were glittering, intense anticipation holding him spellbound for the time being. And then—the wondrous truth!

“Behold!” he cried, shrilly, pointing as he spoke.

“Houses yonder! Cultivated fields, and—see! human beings in motion, who are—”

“Kicking up a great old bobbery, just as though they'd sighted us, and wanted to know—I say, uncle Phaeton, how would it feel to get punched full of holes by a parcel of bow-arrows?”

With a quick motion the air-ship was turned, darting lower and off at a sharp angle to its former course, for the professor likewise saw what had attracted the notice of his younger nephew.

Scattered here and there throughout that secluded valley were human beings, nearly all of whom had sprung into sudden motion, doubtless amazed or frightened by the appearance of that oddly shaped air-demon.

Brief though that view had been, it was sufficiently long to show the professor houses of solid and substantial shape, cultivated plots, human beings, and a little river whose clear waters sparkled and flashed in the sunlight.

It was very hard to cut that view so short, but the professor had not lost all prudence, and he knew that danger to both vessel and passengers might follow a nearer intrusion upon the privacy of yonder armed people. Yet his face was fairly glowing with glad exultation as he brought the aerostat to a lower strata of air, shutting off all view from yonder valley, as it lay amid its encircling hills.

“Hurrah!” he cried, snatching off his cap and waving it enthusiastically, as the air-ship floated onward at ease. “At last! Found—we've discovered it at last! And all is true,—all is true!”

“Found what, uncle Phaeton?” asked Waldo, a bit doubtfully.

“The Lost City of the Aztecs, of course! Oh, glad day, glad day!”

“Unless—what if it should prove to be only a—a mirage, uncle Phaeton?” almost timidly ventured Bruno, a moment later.