INTRODUCTION 

 GEORGE ELLERY HALE 



One of the most striking results of the war is the emphasis 

 it has laid on the national importance of science and research/ 

 The sharp spur of necessity, felt by the Allies soon after the 

 opening of hostilities, drove them to the instant utilization of 

 scientific research to make good the losses caused by the re- 

 striction of imports. Optical glass for gun-sights, range- 

 finders and periscopes ; chemicals needed for high explosives ; 

 and scores of other products developed in Germany after long 

 years of investigation, were suddenly rendered inaccessible. 

 Some of these could be manufactured without much delay; 

 but in many cases the necessary process was unknown, and 

 could only be discovered by research. Investigators from the 

 universities, the industries and the technical schools were called 

 upon for aid, and manufacture was soon rendered possible. 



But the aid thus given was by no means restricted to the 

 duplication of known devices. It shortly became clear that 

 many of the problems of war lie in the domain of the physicist, 

 the chemist, the meteorologist, no less than in that of the mili- 

 tary expert. The physicist was quick to recognize that enemy 

 guns, though completely hidden from view by intervening 

 ground, might be accurately located by sound, and apparatus 

 for this purpose was rapidly developed and employed with 

 great success along the western front. The chemist, when 

 retaliation was forced by the German introduction of poisonous 

 gases, developed new and powerful vapors that led the origin- 

 ators of this system of warfare to regret the step they had 

 taken. The meteorologist, from his observation posts along 

 the battle line, supplied the data needed by the gunner, the 

 sound-ranger, the leader of gas attacks, and the airman. The 

 astronomer studied the trajectories of projectiles, improved the 



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