Mat 30, 1919] 



SCIENCE 



523 



ing a location had been very conservative; a 

 location reported not accurate to within fifty 

 yards was often accurate to within twenty-five 

 yards. In general, the average of a half dozen 

 locations of the same gun taken on different 

 days under differing weather conditions was of 

 a very high order of accuracy; often a matter 

 of but five or ten yards. 



In general a location either by sound or by 

 flash which had been rated " fair " when re- 

 ported to the artillery was found on survey to 

 have been within the unavoidable errors in 

 artillery fire. 



An idea may be gained of the amount of 

 artillery information supplied by the ranging 

 sections from the following figures taken from 

 the reports of the artillery information officer 

 of one of the American corps. This officer had 

 at the time the following sources of informa- 

 tion: three American sound ranging sections, 

 two American and three French flash ranging 

 sections, aviation and observation balloons. 

 During a period of three weeks of rapid ad- 

 vance when the sound sections were out of 

 operation while moving for a considerable por- 

 tion of the time 425 separate locations of 

 enemy batteries were made. Of these the two 

 American flash sections reported 64 per cent, 

 the three French flash sections reported 16 per 

 cent, and the three American sound sections 

 reported 21 per cent. In a period of two 

 weeks when the advance had been checked by 

 the Germans the total number of locations 

 were 392, and the percentages were: From the 

 three American flash sections 38 per cent. ; 

 from the two French flash sections 8 per cent., 

 and from the three American sound sections 

 56 per cent. 



The following figures taken from another 

 and very active sector are also instructive. 

 For a period of three days preparation for an 

 advance the following locations were made: 

 Sound, 22; flash, 22; balloons, 0; aviation, 0. 

 For a period of sixteen days of rapid advance : 

 Sound, 4; flash, 46; balloons, 30; aviation 77. 

 For a period of four days of stabilization : 

 Sound, 6; flash, 34; balloons, 13; aviation, 15. 

 These figures are characteristic. During prep- 

 arations for an advance, both the sound and 



flash sections are very useful and impwrtant 

 sources of information. During rapid advance 

 the sound ranging does not get into action as 

 often or as soon as the flash. In this period 

 the greater part of the information comes from 

 the air observation. 



Both sound and flash ranging have proved 

 their value in the American Expeditionary 

 Forces and are to be retained in the peace- 

 time army; the sound because it is the one 

 source of information wlien all others fail in 

 foggy weather and because thus far no camou- 

 flage has been devised to prevent its working; 

 the flash because of its relatively great mobil- 

 ity and consequent importance in open war- 

 fare. 



Augustus Trowbridce 



Pbinceton Univeesitt 



THE AMERICAN MATHEMATICAL 

 SOCIETY 



The two hundred and third regular meeting of 

 the society was held at Columbia University on 

 Saturday, April 26, extending through the usual 

 morning and afternoon sessions. This being the 

 first eastern meeting since October, the attendance 

 was large, including sixty-seven members, indi- 

 cating, as it may be hoped, a revival of the con- 

 ditions preceding the war. 



President Morley occupied the chair, being re- 

 lieved by Professor Kasner. The election of the 

 following persons to membership in the society 

 was announced: Mr. N. W. Akimoff, Philadelphia, 

 Pa.; Dr. Tobias Dantzig, Columbia University; 

 Mr. A. C. Maddox, Guthrie, Okla., High School; 

 Mr. Montford Morrison, Chicago, HI.; Professor 

 Ganesh Prasad, Central Hindu College, Benares, 

 India ; Mr. F. M. Weida, State University of Iowa ; 

 Mr. C. L. E. Wolfe, University of California. Two 

 applications for membership were received. 



It was decided to hold the coming summer meet- 

 ing of the society at the University of Michigan 

 in the first week in September. Professors Beman, 

 Bliss, Karpinski, Osgood and the secretary were 

 appointed a committee on arrangements for this 

 meeting. A committee was also provided to pre- 

 pare nominations for officers to be elected at the 

 annual meeting in December. 



Professor E. W. Brown, L. E. Dickson and H. S. 

 White were appointed as representatives of the 

 society in the division of physical sciences of thp 

 national research council; and President B. S. 



