XXXIII 



JAMES CLERK MAXWELL 



I 8 3 I - I 8 7 9 



James Clerk Maxwell, born November Jj, iS^i, attended Edin- 

 burgh University 184/-18JO. Entering Cambridge, he graduated sec- 

 ond wrangler in 18^4. He then taught for four years in Marischal 

 College, Aberdeen, and in i860 'was called to King's College, London, 

 where he remained for the following eight years. He early revealed 

 his mathematical genius and before he was nineteen had the honor 

 of reading several pages before the Royal Society of Edinburgh. 

 He developed by mathematics the theory that electricity was a condi- 

 tion of stress or strain in the ether, a wave moving in the same 

 medium as light and traveling at the same rate of speed. The theory 

 was substantiated by the experiments of Hertz, a pupil of Helmholtz, 

 who in i88y proved the existence of the waves which now hear his 

 name. Maxwell died at Cambridge, November 5, i8j^. 



THE MAXWELL AND HERTZ THEORY OF 

 ELECTRICITY AND LIGHT * 



It was at the moment when the experiments of Fresnel were forc- 

 ing the scientific world to admit that Hght consists of the vibrations 

 of a highly attentuated fluid filling interplanetary spaces that the re- 

 searches of Ampere were making known the laws of the mutual ac- 

 tion of currents and were so enunciating the fundamental principles 

 of electro-dynamics. 



It needed but one step to the supposition that that same fluid, the 

 ether, which is the medium of luminous phenomena, is at the same 



* Translated from a paper by M. Henri Poincare. 



320 



