THE 



LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



NOVEMBER 1880. 



XXXVIII. On the new Action of Magnetism on a permanent 

 Electric Current. By E. H. Hall, Assistant in Physics at 

 the Johns Hopkins University* . 



IN the early part of last winter there was published in 

 the ' American Journal of Mathematics 'f an account of 

 some experiments which prove that an electric current, as di- 

 stinguished from the conductor bearing the current, is acted 

 upon by magnetic force in a manner altogether different from 

 that in which ordinary induction is known to take place. The 

 new phenomenon was, in short, the action of a permanent mag- 

 netic force on a permanent electric current. Up to the time 

 when the above-mentioned article was written, this new action 

 had been observed only in one conducting material — gold. 

 In the present article will be given the results of observations 

 with several other conductors ; but first it seems worth while 

 to give some account of various closely related experiments 

 which, though resulting negatively, are not entirely devoid of 

 interest. 



In the previous article the fact was mentioned that a form 

 of apparatus had been devised which, it was thought, might 

 reveal the new action in the shape of an increase of resistance 

 in the conductor. The plan, as modified in accordance with a 



* Printed from a separate impression/communicated by the Author, of 

 the paper in Silliman's American Journal for September 1880. In its ori- 

 ginal form tliis article was a thesis for the degree of Doctor of Philosophy. 

 Some alterations have been made in preparing- it for publication. 



t Vol. ii. p. 287 (1879) ; republished in the Philosophical Magazine for 

 March 1880. 



Phil Mao. S. 5. Vol. 10. No. 63. Nov. 1880. Z 



