Larry Seymour as usual was in charge of the big centrifugal pump—the "All Day Sucker," as the crew had termed the old pump with which coal cargoes were raised.

Everything was working fine. Without a hitch the Nautilus was dropped in the Sound by the Jules Verne until the access tube lay like the hypotenuse of a huge right-angled triangle that had the Jules Verne for its upper apex and the bottom of the sea for its base.

Casting about over the deck of the barge, Jay, who was really the executive officer of the diving chamber with Dick as his assistant, found a suitable spot for a base of operations. Quickly the aquascope of the Nautilus was rolled back and the waters of the Sound lapped at the edges of the trap door.

It was necessary only to make an opening large enough to insert the time bomb that Jay had brought down from the Jules Verne. This was but the matter of a few seconds' work. While Jay worked at the opening Dick arranged the mechanism of the time clock. His knowledge of and his predilection for mechanics made him an expert at this kind of business.

"She's all ready," he told Jay in a few minutes.

"And I'm all ready for you, too, chum," came the reply.

Together they lowered away with their legs through the aquascope until they stood on the deck of the barge. They were in water up to their knees, while the rest of their bodies were safe and dry within the enclosure of the Nautilus. Carefully the bomb was inserted and so held that it would be most likely to rip open a good-sized hole in the deck when it exploded.

"Let's go, chum," counseled Jay as they completed this final phase of their immediate task. So saying they crawled back into the Nautilus and while Dick attended closing and making fast again the aquascope, Jay turned to the telephone to tell Larry they were ready to be raised again.

"You set that bomb to go off soon, didn't you?" called Jay to his chum, as he took down the telephone receiver.