HAYES— U. S. NAVY MV TYPE OF HYDROPHONE. 389 



the same high degree of accuracy. This apparatus, which can not 

 be described at this time, makes use of the MV hydrophone. 



Locating Vessels in Deep Water. 



The experimental results, obtained on the Von Steuben, led to a 

 belief that MV hydrophones could not safeguard navigation in deep 

 water by locating propeller sounds of other vessels. Believing that 

 this weakness could be removed if ships were equipped with a proper 

 type of submarine sound signalling device, a series of experiments 

 were carried out in mid-ocean between the U. S. S. Von Steuben 

 and the U. S. S. Wilkes the latter vessel, a destroyer, being equipped 

 with a submarine oscillator. The tests were conducted in depths 

 varying from i,ooo to 2,500 fathoms. 



The oscillator signals were heard clearly to a range of 35 miles 

 when the Wilkes was abeam and from 10 to 20 miles when ahead 

 or astern of the Von Steuben. 



The range (R) of the Wilkes (see Fig. 4) was determined sev- 

 eral times while she was running ahead of the Von Steuben by 

 measuring the angle ^j which her oscillator signals, reflected from 

 the sea-bottom, made with the horizontal and using for (D) the 

 charted depth which was rather indefinite through the region wherein 

 the experiments were conducted. Nevertheless, these ranges agreed 

 fairly well with values computed from time and speed data or with 

 optical measurements. 



Both theory and subsequent researches indicate that the oscillator 

 on the Wilkes was not best suited for these experiments, but the tests 

 demonstrated beyond a doubt that the hydrophone can safeguard 

 navigation in any depth of water if all vessels are provided with an 

 MV hydrophone and a submarine oscillator. Such an equipment 

 will then give the bearing and course of every vessel within a radius 

 of from 15 to 40 miles. Furthermore, the range of vessels approxi- 

 mately ahead or astern can be roughly determined if the depth of 

 water is known. 



It is quite probable that in the future all sea-going vessels will be 

 equipped with hydrophone apparatus of the MV or other approved 

 type, together with a suitable sound-source. Then maritime law will 



PROC. AMER. PHIL. SOC, VOL. LIX, Y, DEC. I5, I92O. 



