With the double incentive, greed joined to a thirst for revenge, it would not be at all strange if the Moores had risked everything in their efforts to prevent the Sea Lion leaving the Navy Yard on her long trip. It was Ned's private opinion, too, that the son had been the one to sneak into the submarine and attack the Lieutenant with the poisonous gas.
Leaving Frank and Jack in the machine room, Ned and Jimmie entered the water chamber and closed the door, which, however, was provided with a plate glass panel of great thickness, so that light from the other room supplied plenty of illumination.
It was not designed to submerge the Sea Lion until the boys were all ready to step out. Four deep-sea suits hung on hooks in the water chamber, one for each of the boys.
These suits were not much different from those usually worn by deep-sea divers. They were of seamless rubber composition, braced across the breast with bars of steel in order to offset the great pressure of the lower levels and give the lungs plenty of room for expansion.
The helmets, which fitted on the neck of the suits, were lighter than those in ordinary use, but fully as strong. The cords attached to the helmets were very long, and the air-hose admitted of a range of at least three hundred feet.
By the side of each suit lay an electric searchlight of special construction and a long steel pole, shaped something like a crowbar, but very slender and strong. This latter for defense in case attack should be made by some monster of the deep.
"Say," Jimmie grinned, slipping on his suit, "these spring suits look to me like someone to button us up in the back."
"I don't see where you find buttons," replied Ned.
"Look here, then!"
The boy pointed to the screws designed to secure the helmets.