The defenders dropped flat to the deck, outside of the cabin.  A loud yell on the part of the Esquimaux told that they thought the adventurers had been killed, and there was a rush to capture the ship.

“Let ’em have it!  As fast as you can pull the triggers!” cried the old hunter.  “We’ll show ’em what we can do!”

The three guns rang out again and two of the natives fell, both badly wounded.

“I wish we had more help!” exclaimed Andy.  “We’re likely to have trouble soon!  Why don’t those boys come up; in a few minutes they won’t have a chance!”

Indeed it would have been risky now for Jack and Mark to venture out from under the ship, where they were still bravely chipping at the last remaining bit of ice that help the ship fast.  So far their presence had not been noted by the enemy.

At that instant Professor Henderson ran out of the engine room.

“Use the machine gun!” he yelled.  “That is our only hope!”

The next second he fell to the deck, struck by a spear.

CHAPTER XXIX

THE ESCAPE

“He’s killed!” cried Andy.

“Oh Perfessor!  Perfessor!” exclaimed Washington.  “I tole yo’ not to go out.”

“Never mind!  Start the machine gun!” yelled Andy.  “We must fight off these human fiends!”

“Call up the boys!” shouted Bill.  “They’ll be killed under the ship!”

“I’m afraid it’s too late,” said Andy.  “Here, Tom, you help Washington work the machine gun!”

The weapon had been covered by canvas, and, fortunately, the snow had not harmed it.  The canvas was yanked off, and, while Tom prepared to feed the cartridges down the hopper, Washington worked the crank.  In a few seconds there was a fusillade that sounded like a small battery going into action.

From the muzzle of the machine gun poured out a leaden hail.  It struck the Esquimaux fairly and though they tried to stand against it they could not.  Their arrows and spears dropped from their hands and they staggered back, many badly hurt or killed.

“Why don’t those pesky boys come up!” wondered Andy.  His gun was again empty.  He hastened into the cabin to reload the magazine.  As he did so he heard a tapping on the plate glass window set in the floor of the car.

“Who is there?” he cried.

“It’s us; Jack and Mark!” a voice answered.  “Let us up!  The ship is free!”

Andy flung open the window.  It was just large enough for a boy to squeeze through.  In a moment Jack and Mark were in the cabin.

In the meanwhile Bill had dropped his gun and carried the professor from the deck inside.  The old man was unconscious, but a glance showed that the spear had made only a slight wound on the head, and not one that was likely to be dangerous.

“Is he dead?” cried the boys.

“We hope not,” answered Andy.  “But we have no time to lose.  Can one of you start the ship?”