304 
DR. BREWSTER ON THE PHENOMENA AND LAWS 
the ratio of a to b, the major and minor axes of the ellipse, may be thus ex- 
pressed : a : b = sin 2 (3 : rad. 
In steel, where (3=17° and 2 j3 = 34°, we have a: b = 0.559 : 1 = 12 : 21|, 
differing very little from 12 : 22 the actual ratio. 
In silver, where (3 = 39° 48', a: b = 0.9835 : 1 = 17 : 17|. 
In circular polarization, where (3 = 45°, a :b — 1:1, which gives a circle. 
In rectilineal polarization, where (3 = 0, a: b = 0: 1, which gives a straight line. 
It now becomes an interesting subject of inquiry to ascertain the form and 
position of the ellipse, when the angle of incidence on the first plate exceeds 
or falls below the maximum polarizing angle. 
The following experiments were made with silver at angles of incidence of 
80° and 68°, the maximum polarizing angle being 73°. 
Silver. — Angle of Incidence on First Plate 80°. 
Azimuth to 
Complement of Angle of Resto- 
Azimuth to 
Complement of Angle of Resto 
Right. 
ration 
by Second Plate. 
Left. 
ration by Second Plate. 
o 
o / 
o 
o / 
0 
28 2 
0 
28 2 
111 • 
26 35 
111 . 
24 40 
003 , 
“ 2 
25 20 
221 . 
21 0 
33f . 
21 13 
33f 
16 40 
45 
18 20 
45 
14 35 
56i . 
14 20 
501 . 
11 10 
C7| • 
11 32 
07| • 
10 0 
**4 
CO 
■i^C.3 
10 15 
CO 
10 0 
90 
10 0 
90 
10 0 
Silver. — A ngle of Incidence on First Plate 68°. 
O 
o 
o 
o 
0 
. 13 
0 
13 
111 
. 14 
H| • 
13 
22i 
. 151 
221 . 
131 
33f 
. 16 
33f . 
14 
45 
. 17 
45 
14* 
56£ 
. 19 
oei . 
15* 
07| 
. 20 
07| • 
161 
78f 
. 20 
78f . 
18 
90 
. 20 
90 
• • 
20 
In the first of these sets of experiments, the semiaxes of the ellipse are as 10° 
