500 HISTORY OF OPTICS. 



higher mathematics, such as exists in the British 

 universities, who are thus prepared, when an ab- 

 struse and sublime theory comes before the world 

 with all the characters of truth, to appreciate its 

 evidence, to take steady hold of its principles, to 

 pursue its calculations, and thus to convert into a 

 portion of the permanent treasure and inheritance 

 of the civilized world, discoveries which might 

 otherwise expire with the great geniuses who pro- 

 duced them, and be lost for ages, as, in former 

 times, great scientific discoveries have sometimes 

 been. 



The reader who is acquainted with the history 

 of recent optical discovery, will see that we have 

 omitted much which hast justly excited admiration; 

 as, for example, the phenomena produced by glass 

 under heat or pressure, noticed by MM. Lobeck, 

 Biot, and Brewster, and many most curious pro- 

 perties of particular minerals. We have omitted, 

 too, all notice of the phenomena and laws of the 

 absorption of light, which hitherto stand uncon- 

 nected with the theory. But in this we have not 

 materially deviated from our main design ; for our 

 end, in what we have done, has been to trace the 

 advances of Optics towards perfection as a theory ; 

 and this task we have now nearly executed as far 

 as our abilities allow. 



We have been desirous of showing that the type 

 of this progress in the histories of the two great 

 sciences, Physical Astronomy and Physical Optics, 



