.^V DlXKXXIAL KlX'OUl) 13.5 



THE SUBMARINE DETECTOR 



Prof c SHOT M CUV Mason, University of Wisconsin 



Ladies and Gentlemen : 



Our experience in the attempt to develoj) some ways wliicli would 

 aid in combating the German submarine warfare began shortly after 

 our entrance into the war with a meeting called by the National Re- 

 search Council in Washington. Physicists from America were sum- 

 moned to hear a discussion of the ways and means of meeting the sub- 

 marine combat by the British and French naval and scientific men who 

 were sent to America for the purpose of giving American research a 

 running start : and in the course of two or three days we were told of 

 the naval methods of combating the submarines and of the scientific 

 research which had already been started and which had resulted in the 

 perfection and installation of some detective devices. 



We were shocked at that time to realize that the enormous loss 

 through the sinking of ships — that was in the early days of 1918 — were 

 being accomplished by a marvelously small number of submarines. 

 From the experience of the British and French navies combined it 

 was estimated that only 12 or 14 submarines were on duty at one time, 

 and we left that conference with the thought that if 12 or 14 can do this 

 damage, and if submarines can be constructed rapidly and manned 

 rapidly, what an enormous amount of M^aste would result in the near 

 future. 



At that time there was no adequate defense against submarines. 

 The British naval officers summed it up in this way : "I have not much 

 to tell you of our submarine work. It consists of the following action. 

 We get a wireless message that a ship has been torpedoed and we send 

 out a boat to pick up the survivors." About that time the navy's use 

 of depth charges and the institution of the convoy system effectively 

 changed things so that the situation cleared up greatlv. 



In the early days a destroyer would take one or two depth charges 

 and some cans of TNT, 300 pounds each, and if they were dead 

 certain they were near the submarine they would drop a can of TNT 

 thinking they had probably destroyed it. In later days destroyers went 



