"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 moments before.

"Go after Benson, good and hard," whispered Truax.

The cadet looked keenly at Truax.

"You can have a lot of fun with Benson," whispered Truax, "if you fire a lot of questions at him, hard and fast. Benson is a conceited fellow, who knows a few things about the boat, but you can get him rattled and red-faced in no time."

CHAPTER X: A SQUINT AT THE CAMELROORELEPHANT

The big cadet wheeled upon Jack.

"Mr. Benson, how long have you been engaged on submarine boats, sir?"

"Since July," Jack replied.

"July of this year?"

"Yes."

"And it is now October. Do you consider that enough time, sir, in which to learn much about submarine boats?"

"That depends," Skipper Jack replied, "upon a man's ability in such a subject."

"Is it long enough time, sir, for a boy?"

That was rather a hard dig. Instantly the other cadets became all attention.

"It depends upon the boy, as it would upon the man," Jack answered.

"Do you consider, Mr. Benson, that you know all about submarine boats, sir?"

"Oh, no."

"Who does, sir?"

"No one that I ever heard of," Jack answered. "Few men interested in submarine boats know much beyond the peculiarities of their own boats."

"And that applies equally to boys, sir?"

"Yes," Jack smiled.

"Do you consider yourself, sir, fully competent to handle this craft?"

"I'd rather someone else would say it," Jack replied. "My employers, though, seem to consider me competent."

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

"Bra.s.s," Benson replied, promptly.

"Do you know the specific gravity and the tensile strength of this bra.s.s?"

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 pa.s.s 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-cla.s.s 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."

"It is necessary, though," replied Mr. Mayhew. "They are required to do it with all civilian instructors, and it would never do to draw distinctions on account of age. Yes; it is necessary."

When the second squad of cadets arrived, in the afternoon, the three submarine boys found themselves ready for their task without misgivings.

Eph took more part in the explanations than he had done in the forenoon.

Then came a third squad of cadets, to be taken over the same ground. The young men of both these squads used the "sir" at once, having been previously warned by one of the naval officers.

"That will be all for to-day, Mr. Benson, and thank you and your friends for some excellent work," said Lieutenant Commander Mayhew, when the third squad had filed away.

"Say, for hard work I'd like this job right along," yawned Eph Somers, when the three were alone in the cabin. "Just talking three times a day-what an easy way of living!"

"It's all right for a while," agreed Jack. "But it would grow tiresome after a few weeks, anyway. Lying here in the Basin, and talking like a salesman once in a while, isn't like a life of adventure."

"Oh, you can sigh for adventure, if you wish," yawned Eph. "As for me, I've had enough hard work to appreciate a rest once in a while. Going into the town to-night, Jack?"

"Into town?" laughed the young skipper. "I went last night-and some of the folks didn't do a thing to me, did they?"