“Run away!” shouted Andy.  “I’ll tackle the beast!  I’m not afraid!”

“We’re not going to leave you!” yelled Jack.  “I have a revolver!”

Quickly he drew out the small weapon, a present from the inventor.  Taking hasty aim he fired several shots, but his aim was poor.  One bullet struck the bear on the nose, and, instead of stopping the beast, only made him the more angry.

The brute was now but fifty feet away and coming on at a rapid pace over the uneven lumps of ice and snow.

“Run, I tell you!” called Andy.  “Do you boys want to be killed?”

He aimed a furious stroke at the bear, but as he did so his foot slipped and he came down heavily on the ice.  Mark and Jack uttered cries of terror and fright.

With blood dripping from his wounds, foam falling from his red jaws, and with every appearance of rage, the maddened beast rushed on the old hunter.

“He’ll be killed!” yelled Mark.

“If I only had a gun!” groaned Jack.

Andy rolled to one side.  As he did so he uttered a loud cry, and then, to the astonishment of the boys, he disappeared from sight as if the frozen earth had opened and swallowed him up.  At the same time the bear, that was just about to cast himself down on the fallen hunter, seemed to drop down through some hole into the earth.

For an instant Jack and Mark looked at each other with fear in their eyes.

“What has happened?” inquired Mark, in an awestruck voice.

“I don’t know,” answered Jack.  “But look! there are spots of blood over there.  That is where the bear was!”

The boys ran forward.  As they did so their feet seemed to slip from under them.  Down and down they felt themselves going.  Faster and faster they slipped.  They gazed with frightened eyes about them and saw they were on some giant slide of ice, that led into unknown regions.

“Where are we going?” gasped Mark.

“I don’t know!” yelled back Jack.  “At any rate we’re getting a good coast!” He could joke even in the face of danger.

With a jolt the two boys came to the end of their sudden journey.  For a moment they were so startled and shaken up that they could hardly see.  Then, as their senses came back, they gazed around.

There were white glistening walls of ice on every side.  Above glittered a tiny patch of light, showing where the blue sky was.

“Where are we?” asked Mark.

“You’re with me an’ the bear!” exclaimed a voice.

The boys started.  They saw, lying near them, old Andy.  At his feet was the polar bear, dead, with the hunter’s knife sticking in his heart.

“And what place is this?” asked Jack.

“It appears to me like a big ice cave,” answered the hunter.

“Yes, and we’re lost in it,” spoke up Jack, and gave something of a shudder.

“That’s right, my boy,” answered Andy Sudds.

CHAPTER XI