SOUND-RANGING 69 



were thoroughly trained in the duties which they would have 

 to perform, with apparatus identical with that which they 

 would have later to operate. The school was situated in a 

 country where there was excellent opportunity to reproduce 

 field conditions. The men not only worked in day and night 

 shifts as at the front, but were given practice in making rapid 

 changes of position such as they might meet with later in a 

 rapid advance or a forced retreat. A short course in the 

 theory of sound r (and flash-) ranging was given to intelli- 

 gence officers and to the artillery officers who from time to 

 time were detailed to the engineer schools. The ranging school 

 thus not only served the purpose of preliminary training for 

 the ranging companies but also as a center from which in- 

 formation as to the possibilities, limitations, and principles of 

 the new methods of ranging could be disseminated among the 

 officers of the two branches of the service with which the rang- 

 ing sections worked. 



A descriptive pamphlet, of a confidential nature, on ranging 

 was also prepared and distributed for the information of ar- 

 tillery and intelligence officers generally. 



A supply depot of the highly technical material used by the 

 ranging-companies was maintained at the school, and a system 

 of quick delivery by light motor-trucks was set up between 

 the depot and the companies operating at the front. During 

 the period of about eight months (March to November, 1918) 

 during which American ranging-sections operated, work never 

 had to be discontinued, even temporarily, for lack of supply 

 of the highly technical materials used by these sections. For 

 a large portion of this period American sections were oper- 

 ating at widely scattered positions which made the problem 

 of supply a difficult one. 



ORGANIZATION IN THE A. E. F. 



The ranging-service in the American Expeditionary Force 

 consisted of two branches, the sound-ranging and the flash- 

 ranging. One ranging-company was allotted to each American 



