There was a pause, then one of the older cadets turned to Jack to ask:

“What volume of compressed air do you carry at your full capacity?”

“Mr. Benson’s present status,” rapped Mr. Mayhew, quickly, “is that of a
civilian instructor. Any cadet who addresses Mr. Benson will therefore say
’sir,’ in all cases, just as in addressing an officer of the Navy.”

The cadet so corrected, who was at least twenty-one years old, flushed as
he glanced swiftly at sixteen-year-old Jack. To say “sir” to such a
youngster seemed almost like a humiliation. Yet the cadet repeated his
question, adding the “sir.” Jack quickly answered the question. Then two
or three other questions were asked by other cadets. It was plain,
however, that to all of the cadets the use of “sir” to so young a boy
appealed, at least, to their sense of humor.

Through the engine room door Sam Truax and Williamson stood taking it all
in. Sam saw a flash in the eye of one big cadet when the question of “sir”
came up.

Presently the squad filed into the engine room. Here Hal Hastings had the
floor for instruction. He did his work coolly, admirably, though he asked
Jack Benson to explain a few of the points.

Then the questions began, directed at Hal. This time none of the cadets,
under the watchful eyes of Mr. Mayhew, forgot to say “sir” when speaking
to Hastings.

Sam Truax edged up behind the big cadet whose eyes he had seen flash a few