THE STORY OF NINETEENTH-CENTURY SCIENCE 



the Royal Society] were again given publicity in full in 

 his celebrated volume on natural philosophy, consisting 

 in part of his lectures before the Royal Institution, pub- 

 lished in 1807; but even then they failed to bring con- 

 viction to the philosophic world. Indeed, they did not 

 even arouse a controversial spirit, as his first papers had 

 done. 



So it chanced that when, in 1815, a young French 

 military engineer, named Augustin Jean Fresnel, re- 

 turning from the Napoleonic wars, became interested in 

 the phenomena of light, and made some experiments 

 concerning diffraction, which seemed to him to contro- 

 vert the accepted notions of the materiality of light, he 

 was quite unaware that his experiments had been an- 

 ticipated 03' a philosopher across the Channel. He 

 communicated his experiments and results to the French 

 Institute, supposing them to be absolutely novel. That 

 body referred them to a committee, of which, as good 

 fortune would have it, the dominating member was 

 Dominique Frangois Arago, a man as versatile as Young 

 himself, and hardly less profound, if perhaps not quite so 

 original. Arago at once recognized the merit of Fres- 

 nel's work, and soon became a convert to the theory. 

 He told Fresnel that Young had anticipated him as re- 

 gards the general theory, but that much remained to be 

 done, and he offered to associate himself with Fresnel 

 in prosecuting the investigation. Fresnel was not a 

 little dashed to learn that his original ideas had been 

 worked out by another while he was a lad, but he 

 bo\ved gracefully to the situation, and went ahead with 

 unabated zeal. 



The championship of Arago insured the undulatory 

 theory a hearing before the French Institute, but by no 



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