742 COMMEMORATION OF PROF. HENRY A. ROWLAND. 



in the various centers of scientific activity, includinj*' .several months 

 at Berlin in the lalwratory of the greatest Continental ph3'sicist of his 

 time, Von Helmholtz, While there he made a very important investi- 

 gation of the magnetic effect of moving electrostatic charges, a ques- 

 tion of first rank in theoretical interest and significance. His manner 

 of planning and executing this research made a marked impression 

 upon the distinguished director of the laboratory in which it was done, 

 and, indeed, upon all who had any relations with Rowland during its 

 progress. He found what Von Helmholtz himself had sought for in 

 vain, and when the investigation was finished in a time which seemed 

 incredibly short to his more deliberate and painstaking associates, the 

 director not only paid it the compliment of an innuediate presentation 

 to the Berlin Academy, but voluntarih- met all expenses connected 

 with its execution. 



The publication of this research added much to Rowland's rapidly 

 growing reputation, and because of that fact, as well as on account of 

 its intrinsic value, it is important to note that his conclusions have 

 been held in question, with varying degrees of confidence, from the day 

 of their announcement to the present. The experiment is one of 

 great difficulty and the effect to be looked for is very small and there- 

 fore likely to l)e lost among unrecognized instrumental and observa- 

 tional errors. It was characteristic of Rowland's genius that with 

 comparatively crude apparatus he got at the truth of the thing in the 

 very start. Others who have attempted to repeat his work have not 

 been uniformly successful, some of them obtaining a wholly negative 

 result, even when using apparatus apparently more complete and 

 effective than that first employed by Rowland, Such was the experi- 

 ence of Lecher in 188-1, but in 1888 Rontgen confirmed Rowland's 

 experiments, detecting the existence of the alleged effect. The result 

 seeming to be in doubt, Rowland himself, assisted b}' Hutchinson, in 

 1889 took it up again, using essentially his original method, but 

 employing more elaborate and sensitive apparatus. They not only 

 confirmed the early experiments, but were able to show that the 

 results were in tolerably close agreement with computed values. The 

 repetition of the experiment by Himstedt in the same year resulted 

 in the same way, but in 1897 the genuineness of the phenomenon was 

 again called in question by a series of experiments made at the sug- 

 gestion of Lippmann, who had proposed a study of the reciprocal of 

 the Rowland effect, according to which variations of a magnetic field 

 should produce a movement of an electrostatically charged body. 

 This investigation, carried out by Cremieu, gave an absolutely nega- 

 tive result, and ))ecause the method was entirely different from that 

 employed by Rowland, and therefore unlikely to be subject to the 

 same systematic errors, it naturally had luuch weight with those who 

 doubted his original conclusions. Realizing the necessity for addi- 



