“Easily enough,” replied Frank. “I have a diving suit with a storage tank and a generator connected with the helmet. By its means I can travel anywhere under water.”
“A diving suit!”
“Exactly.”
“That will do. But how can you open the door to leave the boat without flooding it?”
“By means of this vestibule.”
Frank placed his hands upon a stopcock; then he continued:
“If you wish to leave the boat, you enter the vestibule from the cabin, presuming that your diving suit is on. You close the cabin door behind you, open this valve, the vestibule fills with water. You open the outer door and walk out. When, you wish to return, simply enter the vestibule, close the outer door, then press this second valve. At once the water is pumped out of the vestibule by pneumatic pressure. When it is empty you may safely enter the cabin. See the idea?”
“Very simple,” agreed Stanhope; “but very ingenious. Lead on.”
They now passed into the cabin.
This was a literal revelation. The famous explorer gazed upon the scene with the deepest of admiration.