THE POLARIZATION OF LIGHT BY REFRACTION. 
135 
action of the first, or of a single surface, which must be obviously more than 
half of the action of the two surfaces, because the planes of polarization have 
been widened before they undergo the action of the second surface. 
In order to obtain the rotation due to a single 
surface, I took a prism of glass ABC (Fig. 2.) 
having such an angle BAG, that a ray RR, 
incident as obliquely as possible, should emerge 
in a direction R r perpendicular to the surface 
AC. I took care that this prism was well 
annealed* and I caused the refraction to be 
performed as near as possible to the vertex A, where the glass was thinnest 
and consequently most free from the influence of any polarizing structure. 
In this way I obtained the following measures. 
Glass. 
Angles of Inclination of Planes ab, cd, (Fig. 1.) 
Incidence. to the Plane of Reflexion. 
87° 38' 54° 15' . 
54 50 47 25 . . . 
32 20 45 22 . . . 
I next made the following experiments with two kinds of glass, — the one a 
piece of parallel plate glass, and the other a piece of very thin crown. The 
latter had the advantage of separating the reflected from the transmitted 
light. 
Plate 
Glass. 
Crown 
Glass. 
Incidence. 
Inclination. 
Rotation. 
Inclination. 
Rotation. 
0° . 
. 45° 0' 
0° 0' . 
. 45° 0' 
. 0° 0' 
40 . 
. 47 28 
2 28 . 
. 47 18 
2 18 
55 . 
. 49 35 
4 35 . 
. 49 19 
4 19 
67 • 
. 52 53 
7 53 . 
. 52 16 
. 7 16 
80 . 
. 58 53 
. 13 53 . 
. 58 42 
. 13 42 
86i . 
. 61 16 
. 16 16 . 
. 61 0 
. 16 0 
I was now desirous of ascertaining the influence of refractive power, although 
I had already determined in 1813, that a greater quantity of light was pola- 
rized, at the same angle of incidence, by plates of a high than by plates of a 
Rotation. 
. . 9° 15' 
. . 2 25 
. . 0 22 
Fig. 2. 
