ou sling 'em into the boat and keep out of his reach."

But Birch had plainly come without any thoughts of treachery. He rowed
up slowly until the prow of his boat scraped the landing, and Bob heaved
the keg and biscuit aboard, shoving off the boat instantly. Without a
word, Birch sullenly fell to work at his oars again and headed for the
island. Mart set down the rifle and descended to the landing.

"Well, if you'll give me a hand wi' this here helmet, lads," suggested
Jerry, "I'll be goin' down."

Bob stepped forward and helped him on with the big helmet, screwing it
down into the collar. Mart stood over the pump wheel, and as he glanced
at the island he saw that Birch had landed, and that he and the others
were carrying up the water and biscuit. It occurred to him that before
dark he must make sure that the boat was shoved out, even if he had to
go ashore in another boat to get it; for it was imperative that the four
mutineers should be unable to leave the island.

However, there was plenty of time left for that, he thought, and so
turned to Jerry. Bob was just completing his task, and Jerry had opened
the front window of his helmet for a parting injunction.

"You'll mind the pumps, lads?"

"You bet!" replied Bob cheerfully.

"Hold on," cried Mart quickly, as the quartermaster began to close his
window. "You sure you've got that kris handy down there, Jerry? You
don't want to take any chances, you know."

"It's there, lad, it's there, eight fathom down," responded Jerry with a
faint chuckle. "It's a-sticking into the old wreck, it is, right where I
can put my hand up to it. Well, lads, mind them pumps now! Good-bye,
lads--here's to the mystery o' the sea, and hoping as the Pirate Shark
ain't around!"

So Jerry collectedly shut himself in and waited until Mart, at the
pumps, had got his diving suit well inflated. Then, disdaining Bob's
proffered assistance, he worked himself to the edge of the landing and
slowly lowered himself over into the water. Bob seized the lines and
paid them out slowly, thus holding Jerry upright and keeping his descent
slow and steady, while Mart pumped slowly and methodically, alternately
watching the flickering helmet down in the green depths and the
pump-gauges.

At length the gauges marked seven fathoms, and the dial finger slowly
rose to eight, then stopped suddenly. Jerry had reached the bottom.

"All right, Holly," said Mart quickly. "Come along an' take the other
wheel."