. 

 [From Nature, Vol. vn.] 



LI. Reprint of Papers on Electrostatics and Magnetism. By Sir W. Thomson, 

 D.C.L., LL.D., F.E.S., F.R.S.E., Fellow of St Peter's College, Cambridge, 

 and Professor of Natural Philosophy in the University of Glasgow. (London: 

 Macmillan and Co., 1872.) 



To obtain any adequate idea of the present state of electro-magnetic science 

 we must study these papers of Sir W. Thomson's. It is true that a great deal 

 of admirable work has been done, chiefly by the Germans, both in analytical 

 calculation and in experimental researches, by methods which are independent 

 of, or at least different from, those developed in these papers, and it is the 

 glory of true science that all legitimate methods must lead to the same final 

 results. But if we are to count the gain to science by the number and value 

 of the ideas developed in the course of the inquiry, which preserve the results 

 of former thought in a form capable of being employed in future investigation, 

 we must place Sir W. Thomson's contributions to electro-magnetic science on 

 the very highest level. 



One of the most valuable of these truly scientific, or science-forming ideas, 

 is that which forms the subject of the first paper in this collection. Two 

 scientific problems, each of the highest order of difficulty, had hitherto been 

 considered from quite different points of view. Cavendish and Poisson had 

 investigated the distribution of electricity on conductors on the hypothesis that 

 the particles of electricity exert on each other forces which vary inversely as 

 the square of the distance between them. On the other hand Fourier had 

 investigated the laws of the steady conduction of heat on the hypothesis that 

 the flow of heat from the hotter parts of a body to contiguous parts which 

 are colder is proportional to the rate at which the temperature varies from 

 point to point of the body. The physical ideas involved in these two problems 



