ON ELECTRICAL INDUCTION IN A MOVING BODY. 209 



XXV. On the Electro -Dynamic effect ivhich the induction 

 of Statical Electricity causes in a moving body. — This 

 induction on the part of the Sun a probable cause of 

 Terrestrial Magnetism. By Professor Osborne Rey- 

 nolds,, M.A. 



Bead February 20th, 1872. 



If an electrified body were placed near a moving conductor 

 so as to induce an opposite charge in the moving body, 

 this charge would move on the surface of the conductor so 

 as to remain opposite the electrified body, whatever the 

 motion might be. If we suppose the moving conductor to 

 be an endless metal band running past a body negatively 

 charged, the positive charge would be on the surface of 

 the band opposite to the negative body, and here it would 

 remain whatever might be the velocity of the band. Now 

 the effect of the motion of this positive electricity on the 

 conductor would be the same as that of an electric current 

 in the opposite direction to the motion of the band. 



If, instead of a band, the moving body consisted of a 

 steel or iron top spinning near the charged body, the effect 

 of the electricity on the top would be the same as that of 

 a current round it in the opposite direction to that in 

 which it was spinning. 



It might be that the electricity in the inducing body 

 would produce an opposite magnetic effect on the top; 

 but even if this were so (and I do not think it has been 

 experimentally shown that it would be so) , its effect, owing 

 to its distance, would be much less than that of the electri- 

 city on the very surface of the top. If we take no account 

 of the effect of the inducing body, the current round the 

 top would be of such strength that it would carry all the 



ser. in. vol. v. p 



