THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



JANUARY 1884. 



I. Electromagnetic Induction in Conducting Sheets and Solid 

 Bodies. By J. Larmor, M.A., D.Sc, Fellow of St. John's 

 College, Cambridge, and Professor of Natural Philosophy in 

 Queen's College, Galway*. 



I. npHE problem of electromagnetic induction in continuous 

 J- conductors has often engaged attention. Maxwell 

 in 1871 (Proc. Roy. Soc, and 'Electricity and Magnetism') 

 gave the complete solution for the case of an infinite sheet, by 

 means of a moving trail of images of the inducing disturbance. 

 He refers to Jochmann (Crelle's Journal, 1866), who had 

 investigated the steady currents that would be set up in an 

 infinite plane or a spherical conductor, rotating uniformly in 

 a field of force, on the supposition that the effect of this ex- 

 ternal field on the conductor is very great compared with that 

 of the system of currents excited. This, we shall find, pre- 

 supposes a velocity of all the parts of the conductor in the 

 immediate neighbourhood of the seat of the disturbance which 

 must not exceed a certain moderate limit, or else a corre- 

 spondingly great resistance. 



In the Philosophical Transactions for 1880 Professor 

 Charles Niven has developed a complete mathematical solution 

 of Maxwell' s equations for infinite plane sheets and spherical 

 sheets of any thickness; but he has not fully discussed any of 

 the simpler cases. The generality of the solution necessarily 

 complicates his expressions; and in what follows we shall, to 



* Communicated by the Author. 

 Phil. Mag. S. 5. Vol. 17. No. 103. Jan. 1884. B 



