At nearly the same moment both Bruno and Waldo caught a glimpse of water, shining clear and distinct amidst that sombre setting; but as yet a tree-crested elevation interfered with the prospect, and it was not until after the course of the air-ship had been materially changed, and some little time had elapsed, that aught definite could be determined as to the actual spread of that body of water.

This proved to be considerable, although it needed but a single look into the professor's face to learn that his eager hopes and exalted anticipations fell far short of realisation.

“Well, it's a sea all right,” generously declared Waldo, giving a vigorous sniff by way of strengthening his words. “I can smell the salt clear from this. A sea, even if it isn't quite so large as others,—what one might term a lower-case c!”

If nothing else, that generous effort brought its reward in the dry little chuckle which escaped the professor's lips, and a kindly glow showed through his glasses as he turned towards Waldo with a nod of acknowledgment.

“Barring the salty scent, my dear boy, which probably finds birth in your kindly imagination. So, on the whole, perhaps 'twould be just as well to term it a lake.”

“One of no mean dimensions, at any rate, uncle Phaeton.”

“True, Bruno,” with a nod of agreement, yet with forehead contracting into a network of troubled lines. “Naturally so, and yet—surely this must be merely a portion? Unless—yet I fail to see aught which might be interpreted as being—”

Promptly responding to each touch of hand upon steering-gear, the aeromotor swung smoothly around, sailing on even keel right into the teeth of the gentle wind, by this time near enough to that body of water for the air-voyagers to scan its surface: a considerable expanse, all told, yet by no means of such magnitude as Professor Featherwit had anticipated.

Too deeply absorbed in his own thoughts to notice the little cries and ejaculations which came from the brothers, he caused the aerostat to rise higher, slowly sweeping that extended field with his glasses.

He could see where several streams entered the body of water, coming from opposite points of the compass, and thus confirming at least one portion of his explained theory; but, so far as his visual powers went, there was no other considerable body of water to be discovered.

“Yet, how can that contracted basin contain all the drainage from this vast scope of country? How can we explain the stubborn fact of—What now, lads?”

An abrupt break, but one caused by the eager cry and loud speech from the lips of the younger Gillespie.

“Looky yonder! Isn't that one o' those sour-us dictionary fellows on a bender? Isn't that—but I don't—no, it's only—”

“Only a partly decayed tree gone afloat!” volunteered Bruno, with a merry laugh, as his eager brother drew back in evident chagrin.

“Well, that's all right. It ought to've been one, even if it isn't. What's the use in coming all this way, if we're not going to discover something beyond the common? And my sour-us is worth more than one of the other kind, after all; get it ashore and you might cook dinner for a solid month by it; now there!”

It was easily to be seen that Waldo had been giving free rein to his expectations ever since the professor's little lecture, but his natural chagrin was quickly forgotten in a matter of far greater interest.

Professor Featherwit had resumed his scrutiny of yonder body of water, slowly turning his glasses while holding the air-ship on a true course and even keel.

For a brief space nothing interfered with the steady motion of the field-glasses, but then something called for a more thorough examination, and little by little the savant leaned farther forward, breath coming more rapidly, face beginning to flush with deepening interest.

Bruno took note of all this, and, failing to see aught to account for the symptoms with unaided eyes, at length ventured to speak.

“What is it, uncle Phaeton? Something of interest, or your looks—”

Professor Featherwit gave a start, then lowered the glasses and reached them towards his nephew, speaking hurriedly:

“You try them, Bruno; your eyes are younger, and ought to be keener than mine. Yonder; towards the lower end of the—the lake, please.”

Nothing loath, Gillespie complied, quickly finding the correct point upon which the professor's interest had centred, holding the glasses motionless for a brief space, then giving vent to an eager ejaculation.

“What is it all about, bless you, boy?” demanded Waldo, unable longer to curb his hot impatience. “Another drifting tree, eh?”

“No, but,—did you see it, uncle?”

“I saw something which—what do YOU see, first?”

“A great big suck,—a monster whirlpool which is hollowed like—”

“I knew it! I felt that must be the true solution of it all!” cried uncle Phaeton, squirming about pretty much as one might into whose veins had been injected quicksilver in place of ordinary blood. “The outlet! Where the surplus waters drain off to the Pacific Ocean!”

“I say, give me a chance, can't you?” interrupted Waldo, grasping the glasses and shifting his station for one more favourable as a lookout.

He had seen sufficient to catch the right angle, and then gave a suppressed snort as he took in the view. Half a minute thus, then a wild cry escaped his lips, closely followed by the words:

“Now I DO see something! And it isn't a drifting tree, either! Or, that is, something else which—shove her closer, uncle Phaeton! True as you live, there's something caught in yonder big suck which is—closer, for love of glory!”

“If this is another joke, Waldo—”

“No, no, I tell you, Bruno! Shove her over, uncle, for, without this glass is hoodooed, we're needed right yonder,—and needed mighty bad, too!”

Little need of so much urging, by the way, since Professor Featherwit was but slightly less excited by their double discovery, and even before the glasses were clapped to Waldo's eyes the aerostat swung around to move at full speed towards that precise quarter of the compass.

“What is it you see, then, boy?” demanded Bruno, itching to take the glasses, yet straining his own vision towards that as yet far-distant spot.

“Something like—oh, see how the water is running out,—just like emptying a bathtub through a hole at the bottom! And see what—a man caught in the whirl, true's you're a foot high, uncle!”

“A man? Here? Impossible,—incredible, boy!” fairly exploded the professor, not yet ready to relinquish his cherished belief in a terra incognita.

The air-voyagers were swiftly nearing that point of interest, and now keen-eyed Bruno caught a glimpse of a drifting object which had been drawn within the influence of yonder whirlpool, but which was just as certainly a derelict from the forest.

“Another floating tree-trunk for Waldo!” he cried, with a short laugh, feeling far from unpleased that the intense strain upon his nerves should be thus lessened. “Try it again, lad, and perhaps—”

“Try your great-grandmother's cotton nightcap! Don't you suppose I can tell the difference between a tree and a—”

“Ranting, prancing, cavorting 'sour-us' right out of Webster's Unabridged, eh, laddy-buck?”

“That's all right, if you can only keep on thinking that way, old man; but if yonder isn't a fellow being in a mighty nasty pickle, then I wouldn't even begin to say so! And—you look, uncle Phaeton, please.”

Nothing loath, the professor took the proffered glasses, and but an instant later he, too, gave a sharp cry of amazement, for he saw, clinging to the trunk of a floating tree, swiftly moving with those circling waters, a living being!

And but a few seconds later, Bruno made the same discovery, greatly to the delight of his younger brother.

“A man! And living, too!”

“Of course; reckon I'd make such a howl about a floater?” bluntly interjected Waldo. “But I'll do my crowing later on. For now we've got to get the poor fellow out of that,—just got to yank him out!”

Through all this hasty interchange of words, the aeromotor was swiftly progressing, and now swung almost directly above the whirlpool, giving all a fair, unobstructed view of everything below.

The suction was so great that a sloping basin was formed, more than one hundred yards in diameter, while the actual centre lay a number of feet lower than the surrounding level.

Half-way down that perilous slope a great tree was revolving, and to this, as his forlorn hope, clung a half-clad man, plainly alive, since he was looking upward, and—yes, waving a hand and uttering a cry for aid and succour.

“Help! For love of God, save me!”

“White,—an American, too!” exploded Waldo, taking action as by brilliant inspiration. “Hang over him, uncle, for I'm going—to go fishing—for a man!”

Waldo was tugging at the grapnel and long drag-rope. Bruno was quick to divine his intention, and lent a deft hand, while the professor manipulated the helm so adroitly as to keep the flying-machine hovering directly above yonder imperilled stranger, leaning far over the hand-rail to shout downward:

“Have courage, sir, and stand ready to help yourself! We will rescue you if it lies within the possibilities of—we WILL save you!”

“You bet we just will, and right—like this,” spluttered Waldo, as he cast the grapnel over the rail and swiftly lowered it by the rope. “Play you're a fish, stranger, and when you bite, hang on like grim death to a—steady, now!”

Fortunately nothing occurred to mar the programme so hastily arranged, for the drift was drawing nearer the centre of the whirl, and if once fairly caught by that, nothing human could preserve the stranger from death.

“Make a jump and grab it, if you can't do better!” cried Waldo, intensely excited now that the crisis was at hand.

The long rope with its iron weight swayed awkwardly in spite of all he could do to steady it, and as each one of the three prongs was meant for catching and holding fast to whatever they touched, there was no slight risk of impaling the man, thus giving him the choice of another and still more painful death.

Then, with a desperate grasp, a death-clutch, he caught one arm of the grapnel, holding fast as the shock came. He was carried clear of the tree, and partly submerged in the water as his added weight brought the flying-machine so much lower.

“Up, up, uncle Phaeton!” fairly howled Waldo, at the same time tugging at the now taut rope, in which he was ably seconded by his brother. “For love of—higher, uncle!”

Then the noble machine responded to the touch of its builder, lifting the dripping stranger clear of the whirling currents, swinging him away towards yonder higher level, where a fall would not prove so quickly fatal. And then the eager professor gave a shrill cheer as he saw the man, by a vigorous effort, draw his body upward sufficiently far to throw one leg over an arm of the grapnel itself.

Knowing now that the rescued was in no especial peril, uncle Phaeton left the air-ship to steer itself long enough for his nimble hands to take several turns of the drag-rope around the cleat provided for that express purpose, thus relieving both Bruno and Waldo of the heavy strain, which might soon begin to tell upon them.

“Hurrah for we, us, and company!” cried Waldo, relieving his lungs of a portion of their pent-up energy, then leaning perilously far over the edge of the machine to encourage the queer fish he had hooked.