THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



DECEMBER 1864. 



LI. On the Theory of Light. — Second Memoir. 

 By Professor L. Lorenz, of Copenhagen*. 



I HAVE communicated, in a previous memoir f " On the 

 Theory of Light," certain theoretical investigations which 

 I have since continued and further developed. But before enter- 

 ing more fully upon the details of the results obtained, I may be 

 allowed to take this opportunity of making a few remarks upon 

 the fundamental principles of the theory, and upon the particular 

 position which it occupies relatively to other theories. 



Researches into the region of mathematical physics bear wit- 

 ness almost universally to a firm belief in the power of inductive 

 reasoning to penetrate to the forces concealed in the interior of 

 bodies, in order, starting from thence as from a centre, to con- 

 struct the explanation and laws of phenomena. This is the path 

 entered upon by Laplace and those of his school : it was sup- 

 posed that the problems of mathematical physics, like those of 

 astronomy, were accessible, even as to their innermost nature, 

 by the inductive method. Molecular forces have been in all 

 cases assumed as the starting-point, which, like the forces of 

 universal attraction, are supposed to be a function of the mutual 

 distances of the molecules, proportional to their masses, and to 

 act only in the direction of the lines joining their centres. The 

 sum of hypotheses involved in this assumption has scarcely been 

 clearly seen ; but how wide the basis is which has been chosen 

 for the erection of almost all manner of wonderful structures has 

 been sufficiently shown by modern analysis. But have these 

 conceptions respecting the nature of molecular forces led to con- 



* Translated from Poggendorff's Annalen, vol. cxxi. p. 579. 

 t Phil. Mag. S. 4. vol. xxvi. p. 81. 



Phil. Mag. S. 4. Vol. 28. No. 191. Dec. 1864. 2 E 



