EXPLANATION OF AN APPARENT NEW POLARITY IN LIGHT.'* 



2% 



and the coefficient of sin -x- (v t — e) \s 



\e C . 2v bh . . „ , . (^-K bh „\1 

 27^|sinx-T + smR + sin(^-^.--RJj 



= 2^6 I ^''^ IT * V >^ (^ + ^°S ^) + S^" ^ X V - COS ^ • T/ j 

 R f ?r6A R . . R . -Kbh^ 



2 • (cosXT-c^^Sg+sin^ -siny^l 



2Xe . irbh R f ?r6A R , . R . iibh 



— T- • Sin -T COS 



TO A,e 



2\e . irbh R 



^^r^-sm-^-coSg-cos 



(irbh _ R\ 

 VXe 2/* 



And the intensity of light on the point of the retina, which is represented by the 

 sum of the squares of these coefficients, is 



. qnbh „ {xbh R\ 



• sm^ -;r cos2 1 -r — I. 



\e \ \e 2/ 





For convenience, put -^ = w, and omit the constant factor 4 h^ ; the expression be- 

 comes then 



where it must be borne in mind that 2<; is a multiple of the distance, of the point of 

 the retina at which the intensity is sought, from the geometrical image of the point 

 of light. It must also be borne in mind that this expression gives the intensity on 

 that point of the retina produced by a single point of light, or a single line of light 

 parallel to the bounding edge of the retarding plate. 



The following Table contains the values of ( j cos^ \w — -x) for every 10° of 



w, and for every 60° of R. In computing them, w has been expressed in degrees : 

 and the last figure of the numbers contained in the Table is the eighth decimal place. 



&2 



