The Operation and Use of the Apparatus 



paper strip, and the distance that the object is from the ship 

 may be determined by the distance between the record of the 

 primary blast and the echo received, as shown in the drawing. 



PLATE 5. System of Mounting the Receivers. 



Observe the markings on the strips of paper shown at the top 

 of the drawing. 



Plate No. 5. Some engineers might imagine that it would 

 be very difficult to mount these delicate instruments on a 

 vibrating ship so as not to interfere with their fine adjustment 



