XI. On a new Analyzer, and its Use in Experiments 



of Polarization. 



By G. B. AIRY, M. A. F. R. Ast. Soc. F. G. S. 



LATE FELLOW OF TRINITY COLLEGE, AND PLUMIAN PROFESSOR OF ASTRONOMY AND 

 EXPERIMENTAL PHILOSOPHY IN THE UNIVERSITY OF CAMBRIDGE. 



[Read March 5, 1832.] 



On two occasions I have had the good fortune to lay before 

 this Society anticipations of optical phenomena founded on theo- 

 retical considerations, which have been fully verified by experi- 

 ment. This agreement I consider important, not because the 

 phaenomena possess any intrinsic value, but because the precise 

 coincidence of observed appearances with theoretical calculations 

 affords the strongest possible proof of the correctness of the 

 theory. I have now to offer another instance of the same kind : 

 in which the experiment was suggested solely by theoretical con- 

 siderations, and in which the appearances, so far as I can observe, 

 agree perfectly with those which theory had indicated. Like the 

 others, it appears to me to give strong evidence of the correctness 

 of all the fundamental assumptions of Fresnel's theory. 



The experiment was first suggested by considerations of the 

 most general kind respecting the use of the analyzing plate in the 

 common polarizing apparatus. When polarized light (whether 

 plane, circular, or elliptical) has passed through a crystalline 

 plate, its intensity, by theory as well as by experiment, is the 



Vol IV. Part II. Ri 



