Fig. 11. The watch officers and the engineer. Left to right: Jentoft, third mate; Layer, engineer; 

 Erickson, first mate; Unander, second mate 



Fig. 12. Steward, cook, and messboys 



Fig. 13. The oscillator of the sonic depth finder installed in the 

 keel. The vibration of this heavy diaphragm sends to the bottom 

 the sound wave whose echo is picked up by the microphones 



