SOUND-RANGING 67 



ability of even a fairly accurate method of location and rang- 

 ing which should not be interfered with by rain or fog and 

 against which the practised camouflage should be unavailing 

 was so obvious that the first successful attempts by the French 

 in 1914 led quickly to the establishment of a ranging service. 



Instruments of four very different types for recording the 

 arrival of the sound of the enemy gun were tried out on various 

 parts of the French front. By 1916 the majority of the French 

 sound-ranging sections were equipped with standardized ap- 

 paratus of one type. A school for the instruction of the per- 

 sonnel of the sections was also established in the back area. 



The standard type of apparatus adopted by the French had 

 the advantage of simplicity and the further advantage that it 

 was for the most part an assembly of well-known commercial 

 apparatus which had been in use in the field telegraph service 

 of the French Army. These were real advantages since the 

 French were obliged to use men in the ranging service who 

 were often unfitted for more active service or for some of the 

 other more highly technical services. There were, however, 

 certain very serious defects in the French apparatus which 

 prevented its adoption first by the British and later by the 

 Americans for neither of whom were the advantages just men- 

 tioned so important as they were for the French. 



By the end of 1915 the British had organized a sound-rang- 

 ing service which employed a photographic recording instru- 

 ment devised by a British subject, resident in France, Mr. 

 Lucien Bull, and which had been tried out with success on the 

 French front but which had not been officially adopted by the 

 French. In the hands of Mr. Bull and Major Bragg, in tech- 

 nical charge of sound-ranging in the British Army, the original 

 apparatus was perfected so as to combine reliability with ample 

 sensitiveness and an extremely quick recovery so that sound 

 ranging could be carried on without confusion during periods 

 of relatively great artillery activity. 



Shortly after the entry of the United States into the war 

 in June, 1917 a French scientific commission arrived in 



