42 HAYES— DETECTION OF SUBMARINES. 



setting which brings a sound into focus causes it to appear binaurally 

 centered and the rotating switch carries a scale and pointer indicating 

 the bearing (ambiguous of course as to port or starboard). 



The ambiguity cannot be removed by comparing the intensity of 

 the sound as given by each line of receivers (the method employed 

 for an "on-board" installation) since there is no sound screen be- 

 tween the two lines. It therefore becomes necessary to make a 

 second compensator setting on two groups of receivers which have 

 their line of centers in a different direction. This can be done by 

 using six receivers in each eel. The direction will then be the com- 

 mon angle of the two compensator settings as has been shown. 



A switching arrangement is provided whereby the twelve re- 

 ceivers in the port eel, or the starboard eel, or the six forward re- 

 ceivers of both eels, or the six rear receivers of both eels can be 

 connected through the compensator to the two telephones. Further- 

 more the compensator is so designed that the last stage of compen- 

 sation, the binaural stage, can be uncoupled and varied independently 

 of the other two stages which may be termed the maximum part of 

 the compensation. Whenever compensation is effected across the 

 two eels, i. e., between the head groups or tail groups of receivers, it 

 will be seen that the binaural part of the compensation must be made 

 independently of the maximum part. 



Suppose a binaural setting has been made on a sound when the 

 12 receivers of, say the starboard eel, are connected through the 

 compensator. The maximum part of the compensation is properly 

 adjusted to bring the impulses from each group of 6 receivers — the 

 head group and the tail group — into phase. The resultant of each 

 group is brought into phase by the binaural part of the compensation 

 and the compensator is so designed that the same angular rotation is 

 required for both stages. Now if the six receivers in the head of 

 the port eel are substituted for the rear six in the starboard eel and 

 in the same order, it is evident that the compensator adjustment for 

 maximum still holds for the reason that this is determined by the 

 angle between the line of the receivers and the sound. This angle 

 remains the same in both cases since the two eels are parallel. But 

 the phase difference between the resultant of the two groups will in 



