Tom Swift and his flying boat;

When the throbbing of the motors ceased and the flying boat had stopped rebounding on its wheels and tail, the party in the pilot room stared at each other in a silence that was pregnant with anxiety. Even Koku, who stood on guard, felt that the situation of the Winged Arrow was serious; yet Koku believed that the “magic” of his Master Tom was equal to almost any emergency.

Tom as a usual thing had plenty of confidence in himself, and especially in his ability to get out of scrapes. But this was one event over which he seemed to have little control.

“What shall we do?” asked Ned.

“Got to find that out, I guess,” admitted the young inventor. “First of all the boys will have to fix that pontoon. It’s a mess. And without it in position the flying boat will be lopsided when I try to raise her.”

“Great!” groaned Ned. “So we are marooned down here at the bottom of this hole in the ice?”

Tom went aft to confer with his mechanicians. Ned and Kingston got into their outer furs, lent an extra coat to Captain Karofsen, and the trio opened the door and by the aid of a light steel ladder got down upon the ice.

The gorge was not more than four hundred feet wide at this point, and the walls of ice towered above their heads at least a thousand feet. If they found it necessary to scale those heights afoot, it would be a difficult and perilous venture.

Tom and the mechanicians came piling out after a bit, and a close inspection was made of the airtight boat pendant from the right wing. It could be repaired, of course; but it necessarily would take considerable time.

“Go ahead,” said Tom. “We have food and heat in plenty. Do your best, Brannigan. Meanwhile the rest of us will take a look through this cañon. I wonder if firing our rifles would attract the attention of Mr. Nestor and the others if they are near here.”

“I tell you what it might do,” said the wireless operator, Kingston.

“What’s that?”

“It might bring down an avalanche of ice on our heads. You know a cracking stick has been known to start an avalanche.”

“Gee!” exclaimed Ned. “I wish you didn’t know so much. Why tell us that? I’ll get a crick in my neck now, I know, watching out for the ice to fall.”

But it was no joking matter. Kingston was right, as Tom well knew. Yet the young inventor felt that they should try as quickly as possible to find Mr. Damon and Mary’s father. If the two were still on the giant iceberg it would be well if they were discovered soon. Tom had no desire to remain marooned at the bottom of this gorge for long.

Captain Karofsen was still cheerfully optimistic about finding his seamen and passengers from the wrecked Kalrye. There were thousands of places in the iceberg where they might conceal themselves. And unless by chance they had seen the seaplane flying over the berg, the castaways would never know that a searching party had come to look for them.

The schooner captain, however, agreed that it would be unsafe to fire the guns. At least, it must not be done down here in the maw of the iceberg.

“We bane look for them—yes? If they haf been here they must leave somet’ing behind. We see where they camp—yes?”

“Come on!” Tom sang out. “We would better keep together. No knowing what there may be on this berg besides castaways.”

“Bears, for instance!” rejoined Ned Newton. “Come on, Koku. Maybe that big spear of yours may be of some use yet.”

The giant grinned and marched ahead with the spear poised for quick use. The party took up their march along the bottom of the gorge, leaving Brannigan and his helpers to repair the flying boat.

From above, as the flying boat had hovered over the ice peaks, the party had gained rather an unsatisfactory idea of what the gorge was like. But, of course, had it not been for the accident to the pontoon Tom would never have descended into the cañon between these towering, icy walls with his invention.

Beyond the place where the Winged Arrow had been forced to land there seemed to be several miles of the gorge, and it was by no means a straightaway cleft in the ice. It twisted and turned like the path of a tortured snake.

“We’d have a fat chance following this cañon in that flying boat,” remarked Ned. “Quick as they got one thing repaired, we’d crash into a spur of this ice and crack something else. I tell you, Tom, just as soon as we can, we want to get up out of this hole.”

“Reckon you are right,” agreed his chum. “Hi! See there! What is it that Koku has found?”

The giant had suddenly increased his stride, thrusting his spear forward and showing every evidence of excitement. He was several rods in advance of the remainder of the party. Tom and the others half expected to see somebody rise up to face the giant, but as they rounded a spur of ice and joined Koku there seemed to be nobody else in sight.

“What is it?” demanded Tom.

“Master see?” exclaimed the giant, and showed them what he had speared.

“Great Scott! A bean can!” cried Tom.

Ned burst into laughter. “Civilization—a sure mark!” he chortled. “Yankees have been here, you may be sure.”

Tom turned to Captain Karofsen.

“How about it, Captain? There is the label still sticking to it. Was that a brand of beans included in the stores of the Kalrye?”

“That iss idt,” rejoined the schooner captain. “They been here—yes. See that cave yonder, Misder Swift? Perhaps they have been there in that cavern.”

Koku had already seen the opening of a considerable cavity in one wall of the gorge. He advanced cautiously. The cavern appeared to be very deep. It was dark beyond the entrance. As the party hesitated before the opening they could distinctly feel a draught of air blowing from the hole.

“It’s a tunnel, I bet,” said Ned. “What say? Think it goes clear through this ice mountain to the plain beyond?”

“Why not?” demanded Tom. “These ice cliffs seem honeycombed with such caves.”

Koku suddenly shouted and darted forward into the mouth of the cave. There was a savage roar in reply—but it was no human voice that answered the giant’s challenge.

“A bear!” exclaimed Tom, and he was first to follow the excited Koku into the half darkened cavity.

Ned was close on the young inventor’s heels.

“Tom, do have a care!” he shouted.

“No time for care!” panted Tom. “Koku’s fearless! No telling what he’ll do!”

The giant thrust mightily with his spear and the challenging roar of the bear changed instantly to a scream of pain. With a crash of ice and breaking spear-handle, the huge beast appeared in the entrance to the cave.

Koku was overturned. He fell sprawling, with the broken handle still clutched in his mighty grip. The bear reared, plucking at the staff that impaled it. It stood taller than Captain Karofsen, or even Koku. It was a drab-white polar bear of fierce aspect, and its rumbling growls reverberated from the walls of ice, making a deafening clamor.

The schooner captain started forward, rifle raised, and in a moment flame darted from the muzzle of his weapon. The bear was hit—indeed, the captain could not have missed it—but it was not yet dead and fell back into the darkness of the cave.

They all advanced, holding their guns ready for another attack. Even Koku scrambled up and came on, brandishing his broken staff. It was fortunate indeed that the three young fellows and their two gigantic companions followed the wounded bear so closely.

Scarcely had the echoing explosion of Captain Karofsen’s rifle died away when a mightier report sounded over their heads. Everybody halted, appalled. The peril of the wounded bear was forgotten. White-faced and motionless, they stared at one another. They all knew that something of vastly greater menace had occurred.

The explosion above was the breaking away of some overhanging shelf of ice. It came sliding and bursting down the face of the cliff and in half a minute was dumped with a terrific shock directly in the mouth of this cave which they had entered.

Powdered ice almost smothered the party for a few moments. Such light as there had been outside the cave in the cañon was snuffed out. The avalanche crowded the cave’s entrance and made the five explorers prisoners with a suddenness that stunned them all.

While from ahead, in the pitch darkness, came again the challenge of the wounded bear. It was by no means hors-de-combat. The wounded brute was full of fight. And to fire again in hope of killing the bear might bring the very roof of the ice cave down upon their heads!