MODERN THEORIES OF HEAT AND LIGHT 



this must mar the progress of scientific truth ; but fortu- 

 nately the story of the introduction of the undulatory 

 theory has a more pleasant side. Three men, great both 

 in character and in intellect, were concerned in pressing 

 its claims Young, Fresnel, and Arago and the rela- 

 tions of these men form a picture unmarred by any 

 of those petty jealousies that so often dim the lustre 

 of great names. Fresnel freely acknowledged Young's 

 priority so soon as his attention was called to it; and 

 Young applauded the work of the Frenchman, and 

 aided with his counsel in the application of the undu- 

 latory theory to the problems of polarization of light, 

 which still demanded explanation, and which Fres- 

 nel' s fertility of experimental resource and profun- 

 dity of mathematical insight sufficed in the end to 

 conquer. 



After Fresnel's admission to the Institute in 1823 

 the opposition weakened, and gradually the philoso- 

 phers came to realize the merits of a theory which 

 Young had vainly called to their attention a full quar- 

 ter-century before. Now, thanks largely to Arago, both 

 Young and Fresnel received their full meed of apprecia- 

 tion. Fresnel was given the Rumford medal of the 

 Royal Society of England in 1825, and chosen one of 

 the foreign members of the society two years later, 

 while Young in turn was elected one of the eight foreign 

 members of the French Academy. As a fitting culmi- 

 nation of the chapter of felicities between the three 

 friends, it fell to the lot of Young, as Foreign Secretary 

 of the Royal Society, to notify Fresnel of the honors 

 shown him by England's representative body of scien- 

 tists ; while Arago, as Perpetual Secretary of the French 



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