The vessel was manned by twenty-seven officers and men. The personnel being as follows: A lieutenant, a sub-lieutenant, two under or petty officers, a physician, a cook and two oilers, two first-class machinists, and seventeen helpers, or seamen, although it was evident, as the captain expressed it, that few of the helpers had seen much sea duty. While it is customary to divide the duties on shipboard into three watches, during the period of twenty-four hours, so as to give each squad a period of service every day at a different period, it would be difficult to carry out the same regulations on board a ship of this character. The captain said: "I notice that they have practically two watches, one taking up the duty from midday until twelve at night, and the other from midnight to noon. Yesterday, I noticed the same shift that was on duty in the morning continued at work all the afternoon, so it is possible that every three or four days shift No. 1, which works from noon to midnight, will be changed so that for the next four days the time for their services will be from midnight to noon." Attention is called to this method of doing duty so that the reader may understand certain events which will be referred to later. The personnel of the shifts was also changed at intervals so that while the lieutenant during one shift would have at work a certain machinist and petty officer, during the next or second shift thereafter another machinist or petty officer would be on duty. In this manner all became efficient, for they had the opportunity afforded of being drilled and handled by different combinations of men and assistants. CHAPTER VII CAUGHT IN THE DEEP SEA NETS The starting of the heavy machinery was sufficient indication that night had come. They were now going up and at an angle which was very perceptible. The boys had become quite expert in detecting certain activities, as they tried in every way to understand the use of the signals. One thing was certain; two sets of bells were brought into play as the signal for changing the motive power. The first signal, three bells followed by two more, was invariably the necessary preparation for this event. A highly pitched bell next gave the signal to stop the gasoline engines and a deep-toned bell indicated the coupling of the electric motor. Occasionally a new set of signals would resound, which they tried to figure out. During the night Alfred thought he had found the key. "Did you notice the big hand wheel on the side of the upright tank, which we pass as we go into the dining room?" he remarked. "That is connected with a large valve," said the captain. "What did you observe?" "Well, did you ever notice that before they rang the shrill bell four times we always have heard a whistle?" asked Alfred. "Why, I have heard the bell ring four times on several occasions without the whistle," contended Ralph.