Harmon looked astonished.

“Ah, yes!” he cried, “but please explain how you can walk out on the deck while the boat is under water.”

Frank smiled.

“There are diving suits,” he said, pointing to several hanging up. “We put those on. The knapsack on the back is the storage reservoir for chemically manufactured air, which keeps us supplied for hours under water.”

They passed now into the pilot-house.

Here were the steering apparatus and the nautical instruments common to all vessels.

The trimmings and fitting of the boat were superb.

From the pilot-house they descended into the cabin.

This was a long compartment elegantly furnished with the finest of appointments.

Staterooms adjoined and electric lights were upon every hand.