But if our friends expected to reach it unmolested they were disappointed. No sooner had they increased their pace than the oxen, with snorts of rage, darted forward. The animals may have imagined they were about to be attacked, and determined to make the first move.

"Here they come!" yelled Ned.

"Sprint for it!" cried Tom.

"Oh, if I only had my gun!" groaned Abe.

It was hard work running over the ice and snow, hampered as they were with their heavy fur garments. They soon realized this, and the pace was telling on them. They were now near to the ship, but the savage creatures still were between them and the craft.

"Try around the other way!" directed Tom, They changed their direction, but the oxen also shifted their ground, and with loud bellows of rage came on, shaking their s.h.a.ggy heads and big horns, while the hair, hanging down from their sides and flanks, dragged in the snow.

"Right at 'em! Run and yell!" advised the young inventor. "Maybe we can scare 'em!"

They followed his advice. Yelling like Indians the four rushed straight for the animals. For a moment only the creatures halted.

Then, bellowing louder than ever they rushed straight at Tom and the others.

The largest of the oxen, with a sudden swerve, made for Mr. Parker, who was slightly in the lead off to one side. In an instant the scientist was tossed high in the air, falling in a snow bank.

"Mr. Damon! Mr. Damon!" yelled Tom, frantically. "Get a gun and shoot these beasts!"

The young inventor and his two companions had come to a halt. The oxen also stopped momentarily. Suddenly Mr. Damon appeared on the deck of the airship. He held two rifles. Laying one down he aimed the other at the ox which was rushing at the prostrate Mr. Parker.

The eccentric man fired. He hit the beast on the flank, and, with a bellow of rage it turned.

"Now's our time!" yelled Tom. "Head for the ship, I'll get my electric gun!"

"We can't leave Mr. Parker!" yelled Abe.

But the scientist had arisen, and was running toward the RED CLOUD.

He did not seem to be much hurt. Mr. Damon fired again, hitting another beast, but not mortally.

Once more the herd of s.h.a.ggy creatures came on, but the adventurers were now almost at the ship, on the deck of which stood Mr. Damon, firing as fast as he could work the lever and pull the trigger.

CHAPTER XIX

THE CAVES OF ICE

"Keep on firing! Hold 'em back a few minutes and I'll soon turn my electric rifle loose on 'em!" yelled Tom Swift as he sprinted forward. "Keep on shooting, Mr. Damon!"

"Bless my powder-horn! I will!" cried the excited man. "I'll fire all the cartridges there are in the rifle!"

Which, at the rate he was discharging the weapon, would not take a long time. But it had the effect of momentarily checking the advance of the creatures.

Not for long, however. Our friends had barely reached the airship, with Mr. Parker stumbling and slipping on the ice and snow, ere the musk oxen came on again, with loud bellows.

"They're going to charge the ship! They'll ram her!" yelled Ned Newton.

"I think I can stop them!" cried Tom, who had leaped toward his stateroom. He came out a moment later, carrying a peculiar-looking gun, The adventurers had seen it before, but never in operation, as Tom had only put some finishing touches on it since undertaking the voyage to the caves of ice.

"What sort of a weapon is that?" cried Abe, as he helped Mr. Parker on board.

"It's my new electric rifle," answered the young inventor. "I don't know how it will work, as it isn't entirely finished, but I'm going to try it."

Putting it to his shoulder he aimed at the leading musk ox, and pulled a small lever. There was no report, no puff of smoke and no fire, yet the big creature, which had been rushing at the ship, suddenly stopped, swayed for a moment, and then fell over in the snow, kicking in his death agony.

"One down!" yelled Tom. "My rifle works all right, even if it isn't finished!"

He aimed at another ox, and that creature was stopped in its tracks.

Mr. Damon had exhausted his cartridges, and had ceased firing, but Abe Abercrombie was ready with his rifle, and opened up on the beasts. Tom killed another with his electric gun, and Abe shot two.

This stopped the advance, and only just in time, for the foremost animals were already close to the ship, and had they rushed at the frail hull they might have damaged it beyond repair.

"Here goes for the big one!" cried Tom, and, aiming at the largest ox of the herd, the young inventor pulled the lever. The brute fell over dead, and the rest, terror stricken, turned and fled.

"Hurrah! That's the stuff!" cried Ned Newton, capering about on deck. He had hurried to his stateroom and secured his rifle, and, before the musk oxen were out of sight he had killed one, which gave him great delight.

"Mighty lucky we drove them away," declared Abe. "They are terrible savage at times, an' I reckon we struck one of them times. But say, Tom, what sort of a gun is that you got, anyhow?"

"Oh, it fires electric bullets," explained our hero. "But I haven't time to tell you about it now. Let's get out and skin one of those oxen. The fresh meat will come in good, for we've been living on canned stuff since we left Seattle. We've got time enough before it gets dark."

They hurried to where the s.h.a.ggy creatures lay in the snow, and soon there was enough fresh meat to last a long time, as it would keep well in the intense cold. Tom put away his electric gun, briefly explaining the system of it to his companions. The time was to come, and that not very far off, when that same electric rifle was to save his life in a remarkable manner, in the wilds of Africa where he went to hunt elephants.

In the cozy cabin that night they sat and talked of the day's adventures. The airship had been slightly lifted up by means of the gas bag, and now rested on a level keel, so it was more comfortable for the gold hunters.

"I did not complete my observations about the great snow slide,"

remarked Professor Parker, "I trust I will have time to go over the ground again to-morrow."

"We leave early in the morning," objected Tom.

"Besides, I don't believe it would be safe to go over that ground again," put in Mr. Damon.

"Bless my gunpowder! But when I saw those savage creatures rushing at you, I thought it was all up with us. Are you hurt, Parker, my dear fellow? I forgot to ask before."

"Not hurt in the least," answered the scientist. "My heavy and thick fur garments saved me from the beasts' horns, and I fell in some soft snow. I was quite startled for a moment. I thought it might be the beginning of the snow movement."

"It was an ox movement," said Ned, in a low voice to Tom.

Morning saw the travelers again under way, with the Red Cloud now floating high enough to avoid the lofty peaks. The weather was clear but very cold, and Tom, who was in the pilot-house, could see a long distance ahead, and note many towering crags, which, had the airship been flying low enough, would have interfered with her progress.

"We'll have to keep the searchlight going all night, to avoid a collision," he decided.

"Are we anywhere near the place?" asked Mr. Damon.

"We're in th' right region," declared the old miner. "I think we're on th' right track. I recognize a few more landmarks."

"There wouldn't have been any trouble if I hadn't lost the map."

complained Tom, bitterly.