THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



JULY 1869. 



I. On some Electromagnetic Phenomena considered in connexion 

 with the Dynamical Theory. By The Hon. J. W. Strutt, 

 Fellow of Trinity College, Cambridge*. 



IT is now some time since general equations applicable to the 

 conditions of most electrical problems have been given, and 

 attempts, more or less complete, have been made to establish an 

 analogy between electrical phenomena and those of ordinary- 

 mechanics. In particular, Maxwell has given a general dyna- 

 mical theory of the electromagnetic field f, according to which 

 he shows the mutual interdependence of the various branches of 

 the science, and lays down equations sufficient for the theoretical 

 solution of any electrical problem. He has also in scattered 

 papers illustrated the solution of special problems by reference 

 to those which correspond with them (at least in their mathe- 

 matical conditions) in ordinary mechanics. There can be no 

 doubt, I think, of the value of such illustrations, both as help- 

 ing the mind to a more vivid conception of what takes place, 

 and to a rough quantitative result which is often of more value 

 in a physical point of view, than the most elaborate mathemati- 

 cal analysis. It is because the dynamical theory seems to be 

 far less generally understood than its importance requires that I 

 have thought that some more examples of electrical problems 

 illustrated by a comparison with their mechanical analogues 

 might not be superfluous. 



As a simple case, let us consider an experiment first made by 

 De la Rive, in which a battery (such as a single Daniell cell) 



* Communicated by the Author, 

 t Philosophical Transactions for 1865. 

 Phil. Mag. S. 4. Vol. 38. No. 252. July 1869. B 



