472 HISTORY OF OPTICS. 



untenable after the fair trial of the two theories 

 in the case of diffraction, and extravagant after 

 Fresnel's beautiful explanation of double refraction 

 and polarization. Even in 1827, in a Treatise on 

 Light, published in the Encyclopaedia Metropoli- 

 tana, he gives a section to the calculations of the 

 Newtonian theory; and appears to consider the 

 rivalry of the theories as still subsisting. But yet 

 he there speaks with a proper appreciation of the 

 advantages of the new doctrine. After tracing the 

 prelude to it, he says, " But the unpursued specu- 

 lations of Newton, and the opinions of Hooke, 

 however distinct, must not be put in competition, 

 and, indeed, ought scarcely to be mentioned, with 

 the elegant, simple, and comprehensive theory of 

 Young, a theory which, if not founded in nature, 

 is certainly one of the happiest fictions that the 

 genius of man ever invented to grasp together 

 natural phenomena, which, at their first discovery, 

 seemed in irreconcileable opposition to it. It is, in 

 fact, in all its applications and details, one succes- 

 sion of 'felicities ; insomuch, that' we may almost be 

 induced to say, if it be not true, it deserves to 

 be so." 



In France, Young's theory was little noticed or 

 known, except perhaps by M. Arago, till it was 

 revived by Fresnel. And though Fresnel's asser- 

 tion of the undulatory theory was not so rudely 

 received as Young's had been, it met with no small 

 opposition from the older mathematicians, and made 



