"I used to be an officer on a French submarine," he replied in a quiet tone, and immediately proceeded to make certain mental calculations. Then he continued: "One inch below the top! That is twenty."
"Twenty what?" asked Ralph.
"Twenty feet; the Germans have the English foot on all their boats. I wonder they didn't think about that, and make a change before starting out."
"Maybe it's twenty meters," said Alfred, with a slight laugh.
"Oh, no," replied the captain. "That would be too Frenchy for the Germans. Besides, it would be too much by all odds. I am sure the conning tower is not more than twenty feet below the surface of the water."
"Then the stern of the submarine must be sticking out of the water," remarked Alfred.
"Unquestionably," replied the captain.
"How far, do you suppose?" asked Ralph.
"We can easily figure that out," said the captain. "Let me see; we must first get the angle at which the boat is lying."