OF NATURAL PHILOSOPHY 263 



would be readily enough explained without the ad 

 mission of an ether. 



(292.) The optical examination of crystallized 

 substances affords one among many fine examples 

 of the elucidation which every branch of science is 

 capable of affording to every other. The indefa- 

 tigable researches of Dr. Brewster and others have 

 shown that the phenomena exhibited by polarized 

 light in its transmission through crystals afford a 

 certain indication of the most important points 

 relating to the structure of the crystals themselves, 

 and thus become most valuable characters by which 

 to recognise their internal constitution. It was 

 Newton who first showed of what importance as a 

 physical character, as the indication of other pro- 

 perties, the action of a body on light might become ; 

 but the characters afforded by the use of polarized 

 light as an instrument of experimental enquiry are 

 so marked and intimate, that they may almost be 

 said to have furnished us with a kind of intellectual 

 sense, by which we are enabled to scrutinize the 

 internal arrangement of those wonderful structures 

 which Nature builds up by her refined and invisible 

 architecture, with a delicacy eluding our conception, 

 yet with a symmetry and beauty which we are never 

 weary of admiring. In this point of view the science 

 of optics has rendered to mineralogy and crystallo- 

 graphy services not less important than to astronomy 

 by the invention of the telescope, or to natural his- 

 tory by that of the microscope ; while the relations 

 which have been discovered to exist between the 

 optical properties of bodies and their crystalline forms, 

 s 4 



