Up to that time not the slightest thing had arisen to give them concern with regard to the working of the engines. These aroused the admiration of the three voyagers by their remarkable performance. Tom declared their equal had never been installed in any plane that was ever built, and Lieutenant Beverly's eyes glowed with satisfaction to hear his pet praised so cordially by one whose good opinion he valued as highly as he did Tom Raymond's.

After Jack had taken his turn at piloting the machine, he amused himself "between naps" by watching the surface of the sea through the binoculars.

"No telling but what I may glimpse a submarine creeping along under the surface," he told the others jokingly. "Then wouldn't we wish we'd brought along a few bombs--the kind they dropped on that Hun bridge the night we went with the raiders. Right now I could almost imagine that shark's dorsal-fin was a periscope belonging to an undersea boat."

Other things came along to cause momentary interest, among them rolling porpoises that rose in sight, and then vanished under the waves, though from their height the boys could easily follow their movements.

Jack was getting a good deal of enjoyment out of the situation, and Tom was glad to notice this fact. He had feared his chum's nerves might give way under the long-continued strain; but apparently Jack had returned to his ordinary condition.

All of them rather dreaded the coming of night. Flying in midocean while daylight lasted was serious enough, but with darkness around for many hours, the situation must awaken new anxieties.

But their hearts were still apparently undaunted. The success that had rewarded their bold starting out gave abundant promise of still better things ahead. Tom resolutely refused to allow himself to have any fear.

What if two thousand miles still lay between them and the goal of their hopes? Was not the miracle-worker of a monster plane doing remarkably fine work, and should they not continue to believe the end justified the means?

So they watched the sun dropping lower and lower in the western sky without any one voicing the thought that must have been in each mind. The same inscrutable Providence that had watched over them by day would still guard them when the light was gone. Under the stars, seeming now so much nearer and brighter than when ash.o.r.e, they went on and on, until back in the east another day dawned, the great day of hope for them!

Jack had taken to looking eagerly ahead once more.

"What do you think you see?" Beverly asked him, for Tom again served as pilot at the steering gear.

"Why, I'm all mixed up about it," came the slow reply. "It certainly isn't a steamer, and again it just can't be land!"

"Well, hardly," Beverly answered. "To tell the honest truth I don't believe there's a foot of land closer to us than the Bermudas, which must lie off in that direction," pointing further toward the southwest.

"When the sun glints on it I'm fairly dazzled," Jack continued, "just as if some one had used a piece of broken looking-gla.s.s to shoot the rays into my eyes. And then there's a sort of queer mist hanging about that thing in the bargain, so that sometimes it's almost blotted out. What under the sun can it be?"

"I think I can give a guess," Tom called back. "How would an iceberg fill the bill, Colin?"

"Just the thing, I'd say," the lieutenant answered, "only who ever heard of an iceberg floating down in mid-Atlantic at this season of the year?

Such a thing would be uncommon, to say the least."

"But not impossible?" ventured Tom, to which the other agreed.

"Take a look, and tell us, Colin," urged Jack, offering the gla.s.ses.

A minute afterwards they were handed bade again.

"Just what it is, Tom, after all," reported Beverly. "A pretty tall berg it seems to be, with an extensive ice-floe around it as level in spots as a floor. I thought I saw something move on it that might be a Polar bear, caught when the berg broke away from its Arctic glacier. We will pa.s.s directly over, and may be able to feel the chill."

"It was the _t.i.tanic_, wasn't it, that b.u.mped into an iceberg, and went down with such a frightful loss of life?" remarked Jack.

"No other," replied Tom. "But we'll try to make sure nothing like that happens to our frail craft. Try to guess what would happen to that monster berg if we hit head on?"

"Hardly a crack!" Jack retorted. "But I'm more interested in wondering what would become of us. Guess we'd better keep a good thousand feet up, and not bother trying to pry into the ice-floe's secrets."

"I'm not dreaming of dropping a foot lower just at present," Tom said decisively; and not one of them dreamed how soon that decision would have to be reversed, since all still looked fair about them, with no storm in sight and the wonderful motors kept up their regular pulsations as if capable of going on forever.

Yet strange vicissitudes and changes are the portion of those who follow the sea; which may also be applied to other voyagers of s.p.a.ce, the sailors of the air. One minute all seems fair, with the sun shining; another, and a white squall is dashing down upon the ship, to catch the crew unawares and perhaps smother them with its mighty foam-crested billows.

It was not half an hour later when something happened that was calculated to chill the hearts of those bold navigators, such as even close contact to the ice-floe and berg could never bring about.

At the time they had reached a point almost above the field of ice from the Arctic regions, and Jack was scrutinizing its full extent, commenting the while on many peculiar features that attracted his attention.

"It's a Polar bear, all right, fellows," he announced, "and believe me he's some size in the bargain. If I had a rifle along I wouldn't mind dropping down there and rustling him. But what ails you, Tom? You seem bothered about something. Gee! you're as white as a ghost!"

Lieutenant Beverly leaned forward and clutched the pilot's arm.

"Anything gone wrong with the motors, Tom?" he demanded hoa.r.s.ely.

"I've just made a terrible discovery," replied Tom, trying to control himself. "The worst has happened, and I'm afraid we're in for a bad time!"

CHAPTER XIX

A DESPERATE CHANCE

"Tell us the worst, Tom!" cried Beverly hoa.r.s.ely.

Jack tried to echo the words, but his tongue seemed to stick to the roof of his mouth. He knew his chum well enough to feel a.s.sured that no ordinary hovering peril could cause the other to look so ashen pale. It must be a frightful catastrophe by which they were threatened, Jack realized.

"The feed pipe! It must be choking up! Latterly I've more than suspected the motors were doing poorer work than before!"

The others understood. Under ordinary conditions they would decide on dropping to the ground for repairs; a task that might be carried out in a brief time, or consume hours, everything depending on the condition in which they found things.

But how utterly impossible to dream of doing anything like that now! Jack looked down to where, in the declining light of the sun, he could see that limitless sea of billowy water. How different indeed all might be were their airship a seaplane, capable of floating on the surface of the water and making a successful launch from it, just as a gull would do.

"I'll take a look, Tom!" Lieutenant Beverly called out. "Not that I doubt what you say, but all of us will have to put our heads together; we shall need all our wits if what you fear proves to be a fact."

Tom was more than willing, in fact he would have himself insisted on the lieutenant or Jack doing this very thing. Pilots differ in plenty of ways; and, as Beverly had said, one might hit on an answer to the problem that had entirely escaped the others.

Jack said not a word, but almost held his breath while Beverly was making his eager examination. The plane was not more than a thousand feet above the sea at most, and going very slowly now.

A short time elapsed. Then Beverly completed his task. The flight lieutenant looked more serious than ever, which told the story even before he uttered a single word.

Apparently the worst had come, and they were up against a question on the answer to which everything, even life itself, depended.

"I'm sorry to say it's a positive fact, boys!" called out Beverly, and as both the others were straining their ears to catch what he said, they had no difficulty in hearing every word.

"It's the supply pipe clogging then?" Tom asked.

"Yes," came the quick answer. "And while under some conditions I've been able to get along for a short time without dropping down, as a rule I've found it wise to look for a landing-place before things got to the point of desperation and avoid a fall, possibly in the midst of a German battalion."

"No chance of our getting at it while afloat, is there?" Jack asked, although he knew what Beverly was bound to say.

"Not the slightest," the other shot back. "It might keep going for something like an hour, and then shut off the gas entirely. Of course there's always a possibility of a miracle happening, such as the obstruction being suddenly overcome; but I'm afraid that's one chance in a million."