THE POLARIZATION OF LIGHT BY REFRACTION. 
139 
Values of 
X. 
Inclination 
observed. 
Inclination 
calculated. 
Difference. 
0° 
. 0° 
0' . 
. 0° 0' 
. 
. 
0° 0' 
H 
7 
10 . 
. 7 20 
-0 10 
5 
9 
40 . 
8 19 
+ 1 21 
10 
. 17 
10 . 
. 16 25 
+ 0 45 
15 
. 24 
42 . 
. 24 6 
+ 0 36 
20 
. 32 
30 . 
. 31 19 
+ 1 11 
25 
. 39 
15 . 
. 37 54 
+ 1 21 
30 
. 44 
10 . 
. 43 5 7 
+ 0 13 
35 
. 49 
38 . 
. 49 28 
+ 0 10 
40 
54 
36 . 
. 54 31 
+ 0 5 
45 
. 58 
40 . 
. 59 5 
-0 25 
50 
. 63 
10 . 
. 63 19 
— 0 9 
55 
. 66 
58 . 
. 67 15 
-0 17 
60 
. 70 
18 . 
. 70 56 
-0 38 
65 
• 74 
8 . 
. 74 24 
— 0 16 
70 
• 76 
56 . 
• 77 42 
— 0 46 
75 
• 79 
20 . 
. 80 53 
— 1 33 
80 
. 83 
23 . 
. 83 58 
— 0 35 
85 
'« 
. 86 
23 . 
. 86 0 
+ 0 23 
90 
. 90 
0 . 
. 90 0 
0 0 
The last column but one was calculated by the formula cot 0 = cot x . (cot 
58° 40') 2 . The differences on an average amount only to 36'. 
In determining the quantity of polarized light in the refracted pencil, we 
must follow the method already explained for the reflected ray, mutatis mu- 
tandis. The principal section of the analysing rhomb being now supposed to 
be placed in a plane perpendicular to the plane of reflexion, the quantity of 
light Q' polarized in that plane, will be 
Q' = 1 — 2 cos 2 <p, 
the quantity of transmitted light being unity. But 
Cot <p = cot x cos (i — i 1 ), . 
and as cot <p = and sin 2 cos 2 <p — 1, we have the quotient and the 
t 2 
