40 



HAYES— DETECTION OF SUBMARINES. 



be towed astern from a moving boat at any desired distance. In 

 principle it is an electrical copy of the M-V Tube above described. 

 Two lines of twelve equally spaced microphone receivers are con- 

 nected through a multiple unit electrical compensator to a head set 



■*-- ■;- 



Plate XYI. The twelve-spot microphone eel and cable reel. 



of two carefully matched telephone receivers. The microphone re- 

 ceiver developed for these lines is fully as sensitive as the " rat" and 

 gives a more faithful reproduction of phase, a requirement for re- 

 ceivers used in multiple. The construction of this receiver is shown 

 in Plate XV. 



Each line of twelve receivers is housed in a flexible gum rubber 

 tube which is stopped at either end by properly streamlined forms. 

 A line of receivers so housed is called an eel. Electrical connection 

 between the receivers and compensator is made through a 14-con- 

 ductor cable which can be payed out or in from a specially designed 

 reel without breaking the electrical circuits. Plate XVI. shows the 

 eel with its cable and reel. Plate XVII. shows the Type AE-2 

 electrical compensator, used to compensate the receivers in the eel. 



The U-3 Tube consists of two similar eels towed abreast, each 

 by its own separate cable. The eels, because of their flexibility, do 

 not skid when eddies or cross currents are encountered and thus 

 keep their relative position without the use of a spreader. Their 



