8 1 The Rev. S. Haughton on the Reflexion of Polarized Light 



A comparison of the columns of differences between the 

 observed results and those calculated from the two theories, shows 

 that they equally well represent the phenomena. 



The value of Q, however, deduced from (1), is 0-278. If this 

 value had been used in calculating Mr. Green's formulae instead 

 of 2*55, the results would have differed widely from the obser- 

 vations. 



The following value for the ratio of J to I may be deduced 

 from Mr. Green's equations, 



ja ^ Q2 cos 2 (j + r ) _|_ s i n 4 r C osec 2 (i — r) .„ . 



F ~ Q 2 cos 2 [i—r) + sin 4 r cosec*(i + r)' ' ' ^ 



This equation differs from that found by M. Cauchy, and 

 cannot be reduced to the same form. 



In the following table I have expressed, as before, the results 

 of both calculations, and compared them with observation, using 

 for Mr. Green's formula the value of Q found from experiment. 



Table II. 

 Transparent Sulphuret of Arsenic, 

 llatio of amplitudes. 

 ^=2-454. Q=2-55. 



From this table it is plain that the formula (3) (considering Q 

 to be an experimental constant, depending on the refractive index 

 and on the reflecting surface) represents the observations at least 

 equally as well as that given by M. Cauchy. 



I have compared the observations of M. Jamin for other sub- 

 stances than sulphuret of arsenic with Mr. Green's formulae, 

 modified as 1 have proposed, and have found the agreement per- 

 fect. The case of sulphuret of arsenic is the severest test of 

 theory given by M. Jamin, as the observations in this case differ 



