They followed Whittam down into the dynamo room, an interesting spot for a machinist. "It's fine," muttered Dan, as he stared about him at the bright metal work, the switch-board and the revolving machines. "But I'm afraid I couldn't learn the use and sense of all this in five years." "Silence in the section," commanded Dave, turning around upon his chum. Whittam now began a short, preliminary talk upon the subjects in which the midshipmen would be required to qualify. "One of the first and most important requests I have to make," said Whittam presently, "is that none of you touch the switches, except by direction. None of you can guess the harm that might follow the careless and ignorant handling of a switch." "It's pretty cheeky for an enlisted man to talk to midshipmen about ignorance," whispered Pennington to Farley. "Oh, I don't know--" Farley started to reply, but Darrin's quiet voice broke in with authority: "Cease talking in section." Farley knew this to be a merited rebuke, and accepted it as such, but Pennington's face went violently red. "Confound that grease-spot-chaser," growled Pen. "He'll be bound to take it out of me as long as the cruise lasts. But I'll get even with him. No cheap greaser is going to ride over me!" That morning none of the midshipmen were called upon to handle any of the fascinating-looking machinery. Nearly the whole of this tour of practical instruction was taken up by the remarks of the chief electrician. As he spoke, Whittam moved over to one piece or another of mechanism and explained its uses. Finally, he began to question the attentive young men, to see how much of his instruction they had absorbed. "This is a shame, to set an enlisted man up over us as quiz-master, just to see how little we know," growled Pennington; but this time he had the good sense not to address his remark to anyone. Pennington was not yet in good shape, after his harrowing experiences of the day before. Ere the tour of instruction was over, he began to shift somewhat uneasily. Then his attention began to wander. A brilliantly shining brass rod near him caught his eye. Something about the glossy metal fascinated him. Once or twice Pen put out his hand to touch the rod, but as quickly reconsidered and drew back his hand. At last, however, the temptation proved too strong. He slid one hand along the rail. "Here, sir, don't handle that!" rasped in the voice of Whittam. Pennington drew back his hand, a flush mounting to his face. "The fellow has no right to talk to a midshipman in that fashion!" quivered Pennington to himself. "But it was the fault of that low-minded greaser Darrin, anyway. Darrin saw me, and he glanced swiftly at the chief electrician to draw attention to me." It is only just to Pennington to state that he actually believed he had seen Dave do this. Darrin, however, was not guilty of the act. He had in no way sought to direct attention at Pennington.