RECEPTION OF THE UNDULATORY THEORY. 471 



very much flattered if you could offer any observa- 

 tions upon it, whether for or against it" Young 

 naturally felt confident in his power of refuting 

 objections, arid wanted only the opportunity of a 

 public combat. 



Dr. Brewster, who was, at this period, enriching 

 optical knowledge with so vast a train of new phe- 

 nomena and laws, shared the general aversion to 

 the undulatory theory, which, indeed, he hardly 

 overcame thirty years later. Dr. Wollaston was a 

 person whose character led him to look long at the 

 laws of phenomena, before he attempted to deter- 

 mine their causes ; and it does not appear that he 

 had decided the claims of the rival theories in his 

 own mind. Herschel (I now speak of the son,) 

 had at first the general mathematical prejudice in 

 favour of the emission doctrine. Even when he 

 had himself studied and extended the laws of dipo- 

 larized phenomena, he translated them into the 

 language of the theory of moveable polarization. 

 In 1819, he refers to, and corrects, this theory; 

 and says, it is now " relieved from every difficulty, 

 and entitled to rank with the fits of easy transmis- 

 sion and reflection as a general and simple physical 

 law:" a just judgment, but one which now con- 

 veys less of praise than he then intended. At a 

 later period, he remarked that we cannot be certain 

 that if the theory of emission had been as much 

 cultivated as that of undulation, it might not have 

 been as successful ; an opinion which was certainly 



