While he hesitated, the walrus rose to the surface.  With a bellow that sprayed bloody foam about him, he charged the cake of ice.  If ever there was need for a cool brain, it was now.  Bruce, gripping his rifle, crouched and waited.  Reaching the cake, the walrus hooked his tusks over its edge till it tilted to a perilous angle.  Bruce’s feet shot from under him, but by a quick movement he caught the upper edge of the ice.  Pulling himself up till he could brace his feet, he took steady aim at the beast’s wild and bloodshot eye.  It was a perfect shot.  The walrus, crumpling, began to sink into the water.  Seeing this, Bruce clung to the cake until the tusk slipped off.  In another moment the uncertain raft was at rest.

“Well, we got him,” he panted, sitting limply on the ice.  “But for mine in the future, give me the cozy dangers of aviation.  I don’t see much relaxation in this game.”

The ice-cake soon drifted so that Bruce could jump ashore.  With their combined efforts the boys were able to draw the dead walrus close in and tie him securely to the ice edge.  Then they returned to camp to send a happy band of natives out for the meat and blubber.

“That head will make a fine trophy to hang in the front parlor of that five-room bungalow,” laughed Barney, as a native brought it in that night.

“You may have it for your den,” said Bruce with a shiver.  “I never want to look a walrus in the face again.”

“To-morrow,” said the Major, as they prepared to retire, “the race will be resumed.”

CHAPTER IX

FIGHTING THEIR WAY OUT

A careful examination of their “ivory jail” showed Dave and the submarine engineer that they were in a narrow chamber completely lined with walrus tusks.  The tusks had been so ingeniously cut and fitted that only the grain of the glistening surface told where one tusk joined another.  As for the door, so closely was it fitted that it was not to be located at all.  In two corners were seal-oil lamps.  These had feed-pipes of some form of dried sea-weeds.  They could thus be fed from without.  Two narrow openings, strongly barred with ivory tusks, one in the floor and one in the ceiling, permitted air to enter, but one peered through them into utter darkness.

“Tain’t no wonder they left us our knives,” grumbled Jarvis.  “The bloomin’ ’eathen knowed we’d wear ’em away before we made any h’impression on that ivory.  But mind you, lad, this hain’t the work of no bloomin’ ’eathen—­not no regular ’eathen it hain’t.  ’E hain’t smart enough for that, your regular ’eathen hain’t.  ’Twas some one else, it was.  Shouldn’t be surprised if it was them three strangers.”

As for Dave, he was worried less about himself than about his companions out in the bay.  Knowing the growing impatience of the Doctor, he was prepared to expect him to attempt anything in case of their prolonged absence.  Should he try to submerge the craft to bring her to land under the ice, it was an even chance every one on board would perish miserably—­caught in the sunken “sub.”