274 
SIR J. CONROY ON THE AMOUNT OF LIGHT REFLECTED 
Table XIIT, 
Crown Glass. 
Per cent, of 
a^i. 
{x - Xi). 
a-2. 
(x — X 2 ). 
incident light 
transmitted. 
6'5 mm. plate. 
July 6, 1888.—Cleaned, but not repolisbed . 
127-2 
1.35-1 
133-1 
129-2 
91-39 
126-9 
135 4 
13-2-7 
129-6 
91-53 
127-7 
134 6 
133-4 
1-28-9 
91-67 
Mean 
91-53 
July 13.—“ Gi'ound grey and rejwlished ” 
125-9 
136-4 
132-3 
1.30-0 
90-70 
by Mr. Hilger 
127-2 
135-1 
133-3 
129-0 
91-11 
126 0 
136-3 
133-1 
129-2 
89-73 
Mean 
90-31 
July 17.—Re-examined. 
125-8 
136-5 
132-2 
130-1 
- 90-70 
126-0 
136-3 
132-0 
130-3 
91-25 
125-9 
136-4 
132-1 
130-2 
90-98 
Mean 
90-90 
11'.5 mm. plate. 
August 13.—Cleaned, but not repolisbed 
. 
187-8 
196-8 
198-0 
186-6 
89-93 
187-9 
196-7 
1975 
187-1 
90-50 
187-8 
196-8 
197-5 
187-1 
90-40 
Mean 
90-28 
11’5 mm. plate bis. 
July 13.—“ Ground gu'ey and repolisbed ” 
126-1 
1.36-0 
132-5 
129-6 
90-69 
by Mr. Hilger 
126-1 
136-0 
133-6 
128-5 
89-18 
125-7 
136-4 
132-4 
129-7 
90-28 
Mean 
90-05 
July 16.—Re-examined. 
1-25-6 
136-5 
132-8 
129-3 
89-.59 
125-6 
136-5 
133-0 
129-1 
89-32 
1-25-5 
136-6 
132-9 
1-29-5 
89-52 
Mean 
89-48 
July 17.—Re-examined. 
124-9 
137-2 
1.31-7 
130-4 
90-14 
124-5 
137-6 
132-0 
130-1 
89-18 
1-24-8 
137-3 
131-7 
130-4 
90-00 
1 
1 
]\Iean 
89-77 
