On Polarization of Light by Reflexion. 
DIAMOND. 
Reffacton. Cheers “4 eet 
24° 12° 45° 0’ 
24 6 34 30 
23 48 24 0 
23 19 14 30 
22 39 4 30 
22 1% L'a & Sen 
20 47 12 30 
18 18 ies | ths 
Inclination of Plane of Polarization 
P xion. 
alculated. 
23 30 
283 
+0 30 
These differences, wk at an average amount to 463’, are also 
within the limits of the errors of observation. * 
Tn all these experiments the value of x was 45°; but in.order to 
determine the law of variation for e, when x varies from 0° to 90°, 
I took a crystal of quartz with a fine natural surface parallel to its 
axis ; and I found that at an angle of incidence of 75°, and when x 
was 45°, the inclination of the plane of polarization to the plane of 
reflexion was 26° 20’. 
results : 
- Values of x. Tactinaton of Pane of Polarization, 
Oi os wh ee Do ee 
TO ae es ee ee 
oo ee. 10 0 10 16 
30 “=f 45 50 16 2 
35 20 QO et EO Ae cw 
40 23 30 22 40 
45 26 20 - 26 27 
50 380 O 30 49 ae 
55 és 35 30 «9023 
60 40°°6 3 40 45 
70 : 53 0 - 53 49 : 
80 70 0 70 29. 
90 90 0 90 0 , 
In these econdianeets the 
The third column 
degree. 
‘(tan 26° 27’) tan x. 
rom these experiments it appears that the formula expresses 
with great accuracy all the changes in the planes of polarization 
I then varied x, and obtained the following 
average error does not-exceed half a 
is computed by the formula tan o= 
