“What is this material, sir?” continued the cadet, resting a hand on a
piston rod.

“Brass,” Benson replied, promptly.

“Do you know the specific gravity and the tensile strength of this brass?”

Before Jack could answer Mr. Mayhew broke in, crisply:

“That will do, Mr. Merriam. Your questions appear to go beyond the limits
of ordinary instruction, and to partake more of the nature of a
cross-examination. Such questions take up the time of the instruction tour
unnecessarily.”

Cadet Merriam flushed slightly, as he saluted the naval officer. Then the
cadet’s jaws settled squarely. He remained silent.

A few more questions and the hour was up.

Lieutenant Commander Mayhew gave the order for the cadets to pass above
and embark in the cutters. He remained behind long enough to say to the
three submarine boys:

“You have done splendidly, gentlemen—far better than I expected you to do.
If you manage the sea instruction as well, in the days to come, our cadets
will have a first-class idea of the handling of the Pollard boats.”

“I wish, sir,” Jack replied, after thanking the officer, “that the cadets
were not required to say ’sir’ to us. It sounds odd, and I am quite
certain that none of the young men like it.”