22 



HAYES— DETECTION OF SUBMARINES. 



sound as received in the two phones its source can be located as to 

 port or starboard. By swinging the boat until the intensity is the 

 same in both phones the direction of the sound can be somewhat ac- 

 curately located as dead ahead. 



Plate VII. Hydrophone installation of Submarine Signal Company. 



The second installation consists of four Fessenden oscillators 

 placed one in each of the four quadrants of a large tank within the 

 ship. Each quadrant is separated from the others by a sound-screen. 

 By comparing the intensity of sound as received on each of the four 

 oscillators the direction of the sound source can be located to within 

 90 degrees. 



Detector installations were early developed at both the Naval 

 Experimental and the Nahant Stations that were superior both as to 

 range and bearing accuracy and the above named devices were aban- 

 doned. 



Two types of detectors have been developed at the Nahant Sta- 

 tion — the " C-Tube " and the " 3-Spot." One type, the C-Tube, has 

 been partially explained. It consists of two rubber acoustic receivers 

 spaced about four feet apart on a horizontal arm which can be 

 rotated about a vertical axis. Each receiver connects to one ear re- 

 spectively through metal tubes ending in stethoscope leads. The 

 direction of a sound is determined by the binaural principle in a 

 manner that has been described. 



The C-Tnbe is a superior detector device. It is capable of giv- 

 ing good range and accurate angular bearings, but its operation is 

 seriously interfered with by local noises and noises from neighboring 

 shipping and it cannot be operated while the boat is moving. More- 

 over, it must be lowered before taking a bearing and must be raised 



