August 25, 1911] 



SCIENCE 



227 



representative in their respective countries : 

 America, Engineering News; England, 

 Engineering ; Germany, Zeitschrift des 

 Vereins Ingenieur ; France, Revue de 

 Mecanique. The first three papers are 

 published weekly, the last monthly. 



To get at the principles of the calculus 

 used, and to what extent, I read the articles 

 in the above journals making use of the 

 principles of the calculus, published dur- 



gently a knowledge of the fundamental 

 principles of the calculus was necessary — - 

 on this basis were the articles and prin- 

 ciples listed. 



The contributors of these articles in- 

 cluded all classes of practising engineers,, 

 army officers, government officials, consult- 

 ing engineers, whether connected with 

 technical institutions or not, and professors 

 in technical schools and universities. That 



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ing the five years 1905-1909. The articles 

 in which the calculus was used were listed 

 and the results shown in Fig. 1. Many 

 articles contained a species of "near cal- 

 culus," thus making the question of in- 

 eluding it or not doubtful ; final disposition 

 of the case was made on the basis of the 

 article including at least one principle of 

 the calculus and employing its nomencla- 

 ture. The authors of the articles made 

 use of the principles as needed, and under- 

 standingly. To read the articles intelli- 



the articles were read by engineers is evi- 

 denced by the numerous comments on the 

 same sent in to the editors, as well as by 

 the records of assistants in libraries spe- 

 cializing in files of technical papers. 



I do not use as a basis the opinions of 

 men as expressed in the journals but rather 

 investigated the principles actually used. 

 The opinions of engineers, as expressed in 

 the journals, were found to vary as much 

 as the oral reports made by the young engi- 

 neers formerly mentioned, and along this 



