HAYES— DETECTION OF SUBMARINES. 



29 



A line of receivers connected in the manner shown in Fig. 2 is 

 termed an M-F Tube. Only sounds from one definite direction, 

 that shown by the arrow, reach the listener's ear in phase and this 

 results in eliminating to a great extent all local surface noises. Such 

 a line of receivers arranged to rotate in a horizontal plane makes an 



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Plate XL Principle of M-F tube 



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excellent maximum instrument. In practice two such lines are 

 mounted side by side with a horizontal separation of about four feet. 

 By connecting the outlet from each line of receivers to the two ears 

 respectively the binaural principle for determining direction can be 

 utilized. In Plate XL a is shown one type of the double M-F Tube 

 designed for use on submarine chasers. 



An instrument of this kind gives a binaural centering of sound 

 at the same time that it is at a maximum, precisely as does the M-B 

 Tube. It is at the same time much freer from water noise than the 

 M-B Tube because it is in focus for sound from only one direction. 

 The M-F Tube has no ambiguity of 180 degrees as has the M-^B 

 Tube and the C-Tube. Because of the combination of these desirable 

 properties, the double M-F Tube is the best rotating hydrophone 

 device that we have. 



The " M-V Tube" is a listening device employing multiple re- 

 ceivers equally spaced in a line and mounted in a fixed position 



