128 Prof. E. C. Pickering on the Polarization of 



Table I. 

 Light reflected when n is near unity, or equals 1 + dn. 



1 









A-B 



Theo- 



Ob- 



Differ- 



i. 



A. 



B. 



i(A+B). 



A + B' 



retical. 



served. 



ence. 



o 







1-000 



1-000 



1000 



0-0 



0-0 



00 



00 



5 



1015 



•985 



1000 



1-5 



10 



10 



00 



10 



1063 



•939 



1001 



6-2 



4-2 



3-5 



+0-7 



15 



1-149 



•862 



1-005 



14-3 



100 



9-0 



+ 10 



20 



1-282 



•752 



1017 



26-0 



18-2 



175 



+0-7 



25 



1-482 



•612 



1047 



41-5 



290 



28-5 



+0-5 



30 



1-778 



•444 



Mil 



600 



420 



410 



+ 10 



35 



2 221 



•260 



1-240 



791 



55-4 



56-0 



-0-6 



40 



2-904 



•088 



1-496 



94-5 



66-1 



670 



—09 



45 



4 000 



•000 



2-000 



1000 



700 



720 



-20 



50 



5-857 



176 



3016 



94-5 



66-1 



680 



-1-9 



55 



9-239 



1081 



5-160 



791 



55-4 



58-0 



-26 



60 



16000 



4-000 



10-000 



600 



42-0 



44-0 



-20 



65 



31-346 



12-952 



22-149 



41-5 



290 



300 



-10 



70 



73-079 



42884 



57-981 



26-0 



18-2 



180 



+0-2 



75 



222-85 



16716 



19500 



14-3 



100 



8-5 



+ 1-5 



80 



1099-85 



971-21 



1035-53 



6-2 



42 



30 



+ 12 



85 



17330-64 



16808-08 



17069-36 . 



1-5 



10 



10 



00 



90 



QO 



CO 



QO 



00 



00 



00 



00 



The most important application of FresnePs formula is to the 

 case of glass, where n somewhat exceeds 1 # 5. The first portion 

 of Table II. gives in an abbreviated form the result of a compu- 

 tation for various values of i, A, B, R, and the polarization of the 

 reflected and refracted rays. When, as frequently happens in 

 the case of plates of glass, the ray passes through several parallel 

 surfaces, a portion of the light reflected back by the second sur- 

 face is again intercepted by the first surface. It may readily be 

 proved that, if A is the amount reflected by a single surface, the 

 amount transmitted including this internal reflection will be 



1 A. 



-=— -—. rr-r-j while if no internal reflection took place it would 



l + (m— DA' r 



be only (1— A) m . In Table II. the values of A, B, R and of 

 the polarization are given for 2, 8, and 20 surfaces, correspond- 

 ing to 1, 4, and 10 plates of glass. In all these cases the index 

 7i=l-55. 



