AND TRANSMITTED BY CERTAIN KINDS OF GLASS. 
251 
Table I. 
A. 
cm. 
cm. 
cm. 
cm. 
cm. 
cm. 
97T 
110-8 
96-1 
110-4 
96-1 
109-6 
97-3 
111-1 
96-8 
110-2 
96-8 
110-0 
96-0 
110-4 
96-7 
109-6 
965 
109-3 
96-3 
111-2 
96-4 
109-8 
96-5 
110-6 
96-3 
109-8 
95-9 
109-3 
95-8 
109-5 
96-7 
110-7 
96-5 
110-0 
95-8 
109-7 
Mean 96-6 
110-7 
96-4 
109-9 
96-2 
109-8 
B. 
94-3 
lOG-3 
93-5 
107-2 
94-6 
107-1 
94-2 
107-3 
94-2 
106-4 
94-5 
106-7 
93-6 
106-5 
93-7 
106-5 
94-0 
107-1 
94-2 
106-8 
93-6 
106-9 
94-3 
107-5 
94-0 
106-8 
94-1 
106-8 
94-4 
106-8 
94-4 
106-9 
94-8 
106-1 
94-4 
107-1 ; 
Mean 94-1 
106-7 
94-0 
106-3 
94-4 
107-0 
Table II. gives the mean readings (1st column), their half difierences (2nd), the 
values oi a — X and h (3rd and 4th), and the percentage amount of light transmitted 
(5th), A and B being the readings made in the two positions of the photometer. 
2 K 2 
