“The hull is of solid steel,” said Frank. “But, though strong and tough, not too heavy.”
The submarine vessel tapered off in the stern to the shape of a fish, while upon the shelving deck or whale-like back were fins or plates of steel.
“The fins keep the boat steady under water,” said Frank.
A platform, with a railing extended along each side of the craft, with a gang-ladder leading up to the hurricane deck and pilot-house, which was upon the vessel’s bow.
Here a search-light was placed.
“Step into the pilot-house,” said Frank, “and I will endeavor to explain to you how the boat’s machinery works.”
Harmon at once complied.
Frank closed the door behind him.
They were in a sort of vestibule made of plates of steel, with a curious shaped pump and lines of hose visible.
“When the boat is submerged,” said Frank, explanatively, “and we wish to go out upon deck, we simply step from the pilot-house into the vestibule, closing the doors. The water is then let in and we open the door and walk out. When we come in we enter this vestibule, close the door, and the water is pumped out. Then we can go back into the pilot-house safely.”