200 PIERCE. 



II. The Electric Compensator. 



Improvement Introduced by Proper Mutual Induction between 



Series Sections. 



9. Brief Description. — In the determination of the direction 

 of submarine sovmd signals and in giving to submarine sound appa- 

 ratus directive qualities so as to permit discrimination of certain sounds 

 from other sounds coming from a different direction, Professor Max 

 Mason ^ of Wisconsin University has made use of two or more sound 

 detectors (rubber nipples in the water) communicating with the ear 

 of the observer through paths (air pipes) capable of adjustment as to 

 time of travel (by adjusting pipe lengths), so that, when the detectors 

 are struck, one after the other, by a sound-wave front, the impulses 

 set up in the transmission paths connected to the several receivers 

 may all be brought to the ear together by a suitable adjustment of 

 retardation by the paths (compensation). In this way the setting of 

 the apparatus (a compensator) to give a maximum of sovmd will, when 

 the apparatus is properly calibrated, give a direct reading of the 

 direction of the incident sound. Sounds coming from other directions 

 (as, for example, noises from the listener's boat) will in general not be 

 compensated to give a maximum of intensity and will be discriminated 

 against by the apparatus. 



Professor Mason developed this apparatus in a form known as the 

 Accoustical System employing rubber nipples on the ends of tubes as 

 sound detectors, and introducing compensation by varying the lengths 

 of air colums through which the resulting sound waves in the air 

 columns were transmitted to the ear of the observer. The Mason 

 system gives excellent results in practice. 



It readily occurred to those who knew of Mason's Device that some 

 advantage might result by using microphones, or other electrical 

 detectors, in the place of the rubber nipples, provided electrical 

 methods could be employed to produce the required retardations of 

 currents set up at the microphones. 



An apparatus for this purpose was devised by me at the Naval 

 Experimental Station at New London, and is called an Electric Com- 

 yensator. 



An Electric compensator is a device for giving electrically to an electric 



1 See H. C. Hayes, Detection of Submarines, Proc. Am. Phil. Soc, Vol. 59, 

 pp. 1-47, 1920: and U.S. Navy MV-T ype of Hydro-phone as an Aid and Safeguard 

 to Navigation, Ibid., Vol. 59, pp. 371-40-4; Max Mason: Submarine Detection 

 by Multiple Unit Hydrophones, Wisconsin Engineer (1921). 



