CONTRIBUTIONS OF PHYSICAL SCIENCE 47 



the flyer in his work at the front, but made possible the so- 

 called ballistic wind corrections upon which the effectiveness 

 of both the artillery and the sound-ranging services largely de- 

 pended. When it is remembered that the biggest element in 

 the effectiveness of a modern army is its artillery and that the 

 effectiveness of the artillery is dependent entirely upon these 

 wind corrections it will be seen how incalculably valuable the 

 work of the trained physicists and mathematicians proved to 

 be to the practical problems of the great war. 



The sixth and last of the new applications of physics to the 

 purposes of the war has to do with the principle of signaling 

 by visible light rays, by infra-red rays, by ultra-violet rays and 

 by super-sound rays. In all of these fields there were develop- 

 ments of great interest and of much importance for the future, 

 though none of them contributed largely to the victory of the 

 Allies. In bombardments all the wire and wireless methods of 

 communication often failed and light signals of some sort were 

 the only reliance. Special signaling lamps were developed by 

 the Science and Research Division of the Signal Corps and 

 ordered in considerable numbers. A notable system of secret 

 signaling with infra-red rays was developed by Theodore Case 

 of Auburn, N. Y., and successfully used in keeping convoys 

 together at night when lights could not be used. The possi- 

 bility of having secret ultra-violet methods of guiding aviators 

 at night back to their landing fields was demonstrated by R. 

 W. Wood. As already indicated super-sound signaling under 

 water was successfully accomplished by Dr. Langevin and ap- 

 plied experimentally in submarine detection. 



Outside the lines of the foregoing classification there were 

 some developments in Physics which deserve mention. Thus 

 a leak proof gasolene tank for airplanes, developed by Dr. 

 Gordon S. Fulcher in collaboration with the Miller Rubber 

 Company of Akron, Ohio, which could be shot through by 

 scores of bullets without leaking a drop of gasolene or catching 

 fire even when the bullets were incendiary, had at the close of 

 the war been ordered placed on all American combat planes. 



