Electromagnetic Effects of Moving Charged Spheres. 285 



might be expected to be double of that of the (equal) com- 

 ponent sounds. The impression upon the observer hardly 

 corresponded to this anticipation. It was difficult to say that 

 the compound sound was decidedly the louder ; although the 

 accession of the second sound as an addition to the first could 

 always be distinguished, and this whether the higher or the 

 lower sound were the one added. It may be remarked that 

 the question involved in this experiment is partly physiological, 

 and not merely mechanical as in the case of sounds nearly in 

 unison, 



Terling Place, Witham. 



XXVI. The Electromagnetic Effects of Moving Charged 

 Spheres. By Edwin P. Adams *. 



THE magnetic effects due to moving charges were first 

 shown experimentally by Professor Rowland f in 1876. 

 Dr. E. LecherJ, in 1884, thinking that the importance of the 

 experiment made it desirable to repeat, it did so, but with 

 negative results. Insufficient data regarding his experiment 

 make it difficult to point out the cause of his failure to 

 obtain the effect. Since then, Professor Rowland's results 

 have been fully confirmed by Professor W. 0. Rontgen § in 

 1885, by Rowland and Hutchinson || in 1889, and by Pro- 

 fessor F. HimstedtIF later in the same year. 



The next experimental attack upou this problem was by 

 M. V. Cremieu ** at Paris in 1900-01. His experiments 

 were originally undertaken to determine whether a changing 

 magnetic field exerts a mechanical force upon an electrically 

 charged body. The negative results obtained led him to 

 undertake a series of experiments on the magnetic effect of 

 moving electric charges. The results of these experiments 

 are apparently all opposed to the results obtained by the 

 above observers. The data which have thus far appeared do 

 not give sufficient details to render it certain that positive 

 results should have been expected. Cremieu himself states 

 that he is convinced that the effect does not exist. 



The great importance of the experiment would seem to 



* Communicated by Prof. J. Trowbridge, 

 t Am. Jour. Sci. (3) xv. p. 30 (1878). 

 X Rep. d. Phys. xx. p. 151 (1884). 

 § Site. d. Berlin. Akad. p. 198 (1885). 

 || Phil. Mag-. [3] vol. xxvii. p. 445 (1889). 

 H Wied. Ann. xxxviii. p. 560 (1889). 



** Comptes Rendus, cxxx. p. 1544 ; cxxxi. pp. 578, 797 (1900) ; cxxxii. 

 p. 327 (1901). 





