68 THE NEW WORLD OF SCIENCE 



Washington with information regarding a number of the new 

 scientific activities in the French Army. This commission 

 reported that four radically different systems of sound-rang- 

 ing were at that time in use in the French Army and recom- 

 mended that an instrument of each of the four types be con- 

 structed in America from rough sketches which were furnished 

 and that a comparative test of the four types be carried out at 

 an artillery firing field. The members of the commission stated 

 that such a test had not been carried out in Europe and that 

 it was regarded as highly desirable that such a test be carried 

 out impartially in America. The commission had data on the 

 original Bull apparatus but not on the apparatus as perfected 

 for the British; this was unfortunate, as it rendered the com- 

 petitive test incomplete and the conclusions drawn from the 

 test subject to revision later. ^ 



The present writer was charged with carrying on the pre- 

 liminary test and the construction of a field-set of the type 

 which should be judged most satisfactory. Before construc- 

 tion was started the writer secured permission to go to France 

 to study the various systems in actual use in the field and so 

 became aware of the progress which the British had made in 

 time to stop construction on the type first decided upon and 

 to start construction of apparatus in quantity of the Bull type 

 and to insure that the experimental work in America be along 

 lines determined by field rather than laboratory experience. 



By the end of 1917 the first American troops assigned for 

 the ranging-service were available from the replacements al- 

 ready in France. The original group of about forty enlisted 

 men were given instruction by a small group of officers who 

 had been trained on the British front in the theory and prac- 

 tical application of sound-ranging, and an American school 

 was formed as a part of the Army Engineer Schools near 

 Langres. All of the five companies which ultimately came to 

 France to carry on the ranging-service (both sound and flash), 

 were put through this school before they were sent to the front. 

 The instruction covered a period of one month and the men 



