That he and Jarvis might be kept prisoners indefinitely seemed certain, for after some five or six hours, food was thrust in to them and they were left, apparently for the night.  The food consisted of boiled fish and liver, probably walrus liver, soaked in rank seal oil.  They ate a little fish and thrust the liver through the opening in the floor, the better to escape its nauseating odor.

“H’I’d die before h’I’d h’eat ‘is bloomin’ victuals,” snarled Jarvis contemptuously, “that bloomin’ ’eathen!”

He began poking about the narrow confines of the jail.  Not being able to see to suit himself, he struck a match and touched it to the mass, placed on the edge of a brimming seal-oil lamp, in lieu of a wick.  Immediately a line of fire was kindled and its light, reflected again and again by the dazzling whiteness of their prison walls, made the whole place as light as day.  At once Jarvis gave a cry of surprise and began crawling toward the farthest side.

“H’I told you there was minerals,” he exclaimed.  “E’s a rich un, this bloomin’ ’eathen.  H’it’s gold, h’I’ll be blowed!”

He began digging away with his knife at some yellow spots in the ivory.  They were bits of inlaid gold.

“What’s the idea?” asked Dave in surprise.  “Are all prisons up here made of ivory inlaid with gold?”

“Y’ can’t tell, lad.  ‘E’s a queer one, the bloomin’ ’eathen, and if h’I be ’anged,” sputtered Jarvis, “what’s one pole more or less, when you’ve gold calling to come and take it.  What—­”

He paused, his mouth agape, words unsaid.  The door of the ivory den had been softly opened, and framed in it were the dark, crafty faces of the three natives who had brought about their captivity and imprisonment.  In their hands gleamed knives with long blades of a curious oriental type.

* * * * *

But we must return to the Doctor and his crew of gobs who had been left on the submarine.

When the young captain and his chief engineer did not return at sunset, deep concern for their safety was felt.  Three searching parties were sent out, while, from time to time, flares were lighted to show them the way to the submarine, should they chance to have lost their directions on the ice-floe.  The flares guided the searching parties back to the boat, but so far as finding trace of the missing ones was concerned, neither flares nor searchers were of any avail.

In the meantime, the Doctor paced the deck anxiously.  They were losing valuable time.  If only they could find a way to shore, the damaged shaft might be repaired and, during the interval, the captain and engineer would doubtless turn up.

At the first hint of dawn the watch discovered a lead half-way through the ice-floe.  At once the Doctor ordered the submarine run into this narrow channel.  The result was what might have been expected; the ice closed in and the “sub” was locked in the center of the floe.  There remained but one way it could move—­down, under the ice.  Otherwise, it might drift indefinitely in this solid mass of ice.  They would be carried away from the bay, away from their friends, and all hope of rescuing them would be lost.  It was, indeed, a terrible plight.