to see it, and they were not sure of the
quartermaster's exact position. In the same brain-flash he realized that
Jerry would have some minutes of life, due to the air contained in his
inflated dress; there was time for him to get down with a spare line and
get Jerry up, if he acted promptly. So he had acted.

He had pictured in his mind the scene below, with that three-foot kris
sticking out from the side of the wreck. The instant those bubbles
appeared, he knew there was danger; and the instant he hauled up the
clean-severed ends, he guessed that the line and hose had brushed
against the keen kris and had been parted. Bob's startled cry had
appalled him for an instant, but they had seen no shadow in the green
depths, and he leaped at the true solution without hesitation.

"Get that helmet screwed on, now," he snapped, seeing that Bob had
connected the air hose. "You keep your nerve, old scout! Everything
depends on you, up at this end, so don't get flustered. Chase up and get
a coil o' rope. I'll send Jerry up to you first. Haul him up slow,
remember."

Bob, who had recovered his nerve under Mart's apparent calm, dashed up
the ladder and was down again with a coil of light line. The helmet was
screwed down tightly, and Mart pressed his chum's hand warmly. Then,
taking one end of the spare line and knotting it around his waist beside
his own life line, he drew his sheath knife in case of emergency and
stood waiting for his dress to inflate.

He had concealed his own fear behind his frantic haste, and now he did
not hesitate to admit to himself that he _was_ afraid--and very much
afraid, too. Oddly enough, the thought of the Pirate Shark did not cause
him any great concern. While all during the voyage he had looked forward
to diving, now that he was about to step off into that forty feet of
water he would have given anything in the world to be able to stay up
above.

But the thought of Jerry drove him steadily to the task. Picturing the
old man down in the depths, hoping agonizingly for some shred of help
from the two boys to whose hands he had trusted himself, Mart resolutely
set himself to conquering his fears. The life of a man depended on his
keeping up courage and on his remaining cool-headed. When he felt that
his dress was full of air, he looked at Bob through the thick glass of
the side-plates in his helmet, then sat down and resolutely lowered
himself over the edge.

He very nearly overbalanced in doing