INDEXED. 



THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[SIXTH SERIES.] 



DECEMBER 1901. 



LVII. On the Induction-Coil. By Lord Rayleigh, F.R.S.* 



ALTHOUGH several valuable papers relating to this 

 subject have recently been published by Oberbeck f, 

 Walter^, Mizuno §, Beattie ||, and Klingelfuss T, it can 

 hardly be said that the action of the instrument is well 

 understood. Perhaps the best proof of this assertion is to be 

 found in the fact that, so far as I am aware, there is no 

 a priori calculation, determining from the data of construction 

 and the value of the primary current, even the order of 

 magnitude of the length o£ the secondary spark. I need 

 hardly explain that I am speaking here (and throughout 

 this paper) of an induction-coil working by a break of the 

 primary circuit, not of a transformer in which the primary 

 circuit, remaining unbroken, is supplied with a continuously 

 varying alternating current. 



The complications presented by an actual coil depend, or 

 may depend, upon several causes. Among these we may 

 •enumerate the departure of the iron from theoretical behaviour, 

 whether due to circumferential eddy-currents or to a failure 

 of proportionality between magnetism and magnetizing force. 

 A second, and a very important, complication has its origin 



* Communicated by the Author from the Jubilee volume presented to 

 Prof. Bosscha. 



+ Wied. Ann. lxii. p. 109 (1897) ; lxiv. p. 193 (1898). 

 \ Wied. Ann. lxii. p. 300 (1897); lxvi. p. 623 (1898). 

 § Phil. Mag xlv. p. 447 (1898). 

 || Phil. Mag. 1. p. 139 (1900). 

 1j Wied. Ann. v. p. 837 (1901). 



Phil. Mag. S. 6. Vol. 2. No. 12. Dee. 1901. 2 Q 



