Dimly he felt, rather than saw, a dark shadow pass over them.  As in a dream he whispered the magic formula: 

“One—­seven—­ten—­three—­five.”

Faintly he heard the grind of the wheels, felt the fan’s breath on his cheek, then all was lost in unconsciousness.

* * * * *

After ten solid hours of sleep the airplane party awoke to find their dogs whining and pawing at the entrance to their shelter.

“Guess they’re hungry,” said Barney, rubbing his eyes sleepily.  “Now if we could only locate a seal in some water-hole, it would help out our scanty supply of food.”

“Suppose we try,” said Bruce, slipping into his skin garments and looking to his rifle.

“All right,” said Barney, and without delay they were hurrying to a pressure ridge of ice from whose top they might hope to locate the nearest water-lead.  This took them some distance from their camp, but since the air was still and the moon flooded everything with light as of day, this did not worry them.

They had reached the height, and were scanning the long lead of water something like a mile to the left of them, when Bruce gave a cry of surprise, and, pointing to the south end of the lead, exclaimed: 

“What’s that immense black thing rising from the water?  Can’t be a whale up here, can it?”

“Impossible!  And, look!  There’s something rising from the center of it!  It can’t be—­yes—­it is!  It’s the submarine!”

Barney tumbled from the ice ridge and went sprinting away over the ice.  His boyhood pal, Dave Tower, was on that submarine.

With greater deliberation, Bruce attracted the attention of the Major.  Together they hurried after their companion.

The sight that met their eyes as they reached the edge of the water-channel filled them with consternation.  The Eskimo boy and Barney were hurriedly carrying limp, motionless forms from the submarine into the outer air.

Their worst fears were groundless, however, for after two hours of faithful work they restored the last one of the crew to consciousness.  The last to recover was the Doctor.

“Which goes to prove,” smiled Dave, “that when you most need a doctor, that’s the time he’s most likely to be sick.”

There was a moment of joyful reunion between the two pals, Barney and Dave.  As for the explorers, after the danger had passed, they seemed to take little notice of one another.

The Doctor soon was able to rise unsteadily, and, supported by two of his men, he dragged himself back and forth across the ice.  When, at last, he had full possession of his faculties, he suddenly darted into the submarine, reappearing a moment later with instruments.