^-^ 



HAYES— DETECTION OF SUBMARINES. 



41 



horizontal distance remains the same as that between their respec- 

 tive cables at the boat's stern with but slight variation. 



Every unit in the construction of an eel (head, tail, housing tube, 

 and each of the twelve receivers) is carefully designed to have neu- 

 tral buoyancy in sea water when the eel is filled with fresh water. 

 This assures that the line of receivers will lie in a horizontal plane 



Plate XVII. The AE-2 electric compensator designed to accommodate two 



sets of i2-spot microphone lines. 



so long as there is any appreciable relative motion between the eel 

 and the water. The depth at which the eels trail depends upon the 

 length of cable and the speed of the boat. In practice this depth is 

 kept within lOO feet. 



The electrical impulses from the microphone receivers, produced 

 by sound from any particular direction, are brought into phase at the 

 two telephone receivers by means of a rotating switch arrangement 

 which introduces the proper amount of loaded line into the separate 

 microphone circuits. The 6 microphones in the forward half of the 

 receiver line attach to one telephone and the rear 6 connect with the 

 other. The construction of the compensator is such that the same 



