AND TRANSMITTED BY CERTAIN KINDS OF GLASS. 
253 
Crown Glass. 
15 mm. plate, a; = 5 mm. 
A. 
Eeadings. 
Half 
differences. 
a — X. 
b. 
Percentage of 
light transmitted. 
Percentage of 
light transmitted. 
Mean of A and B. 
cm. 
cm. 
95-5-107-1 
5-8 
1957 
207-8 
88-69 
95-8-106'9 
6-5 
I960 
207-5 
89-22 
95-6-106'6 
5-5 
196-0 
207-5 
89-22 
89-04 
B. 
94-3-104-9 
6-.3 
196-2 
207-3 
89-58 
94-0-105-2 
5*6 
195-9 
207-6 
89-04 
94-2-105-4 
5-6 
195-9 
207-6 
89-04 
89-22 
89-13 . 
Crown Glass. 18'5 mm. plate, x = Q mm. 
A. 
Eeadiogs. 
Half 
differences. 
a — X, 
b. 
Percentage of 
light transmitted. 
Percentage of 
light transmitted. 
Mean of A and B. 
cm. 
cm. 
97-1-108-7 
5-8 
195-6 
207-8 
88-60 
96-7-109-0 
6-1 ' 
195-3 
208-1 
88-08 
96-2-108-1 
5-9 
195-5 
207-9 
88-43 
88-37 
B. 
94-7-105-8 
5-5 
195-9 
207-5 
89-13 
94 - 6 -IO 6-4 
5-9 
195-5 
207-9 
88-13 
94-6-106-4 
5-9 
195-5 
207-9 
88-43 
88-66 
88-51 
