AND TRANSMITTED BY CERTAIN KINDS OF GLASS. 
277 
Table XIV. 
Flint Glass. 
• 
Per cent, of 
a-j. 
{x - a-i). 
X.2. 
{x - .r.,). 
incident light 
transmitted. 
7 mm, thick. 
September 30, 1888.—Cleaned, but not re- 
187-6 
197-1 
194-8 
189-9 
92-78 
polished 
187-7 
197-0 
194-7 
190-0 
92-98 
187-5 
197-2 
195-1 
189-6 
92-40 
187-5 
197-2 
195-0 
189-7 
92-50 
Mean 
92-66 
49 mm. thick. 
August 15.—Surface repolished with putty 
18.3-0 
200-1 
198-4 
184-7 
85-14 
powder on August 14 
182-5 
200-6 
197-8 
185-3 
85-23 
182 9 
200-2 
198-1 
185-0 
85-.32 
183-1 
200-0 
198-5 
184-6 
85-14 
l\Iean 
85-21 
August 16.—Re-examined. 
182-8 
200-3 
198-7 
184-4 
84-70 
183-2 
199-9 
198-0 
185-1 
85-68 
182-7 
200-4 
198-1 
185-0 
85-15 
Mean 
85-18 
August 16.—Repolished with putty powder 
183-1 
200-0 
198-1 
185-0 
8.5-50 
and examined immediately 
182-3 
200-8 
198-9 
184-2 
84-08 
182-5 
200-6 
199-1 
184-0 
84-08 
1 
Mean 
84-55 
August 18.—Re-examiued. 
183-0 
200-1 
198-8 
184-3 
84-78 
182-7 
200-4 
198-7 
184-4 
84-61 
182-7 
200-4 
198-6 
184-5 
84-70 
Mean 
84-70 
69'5 mm. thick. 
August 15.—Cleaned, but not repolished 
182-1 
200-2 
198-5 
183-8 
84-22 
181-9 
200-4 
193-4 
183-9 
84-13 
182-1 
200-2 
198-0 
184-3 
84-67 
182-4 
199-9 
198-6 
183-7 
84*40 
Mean 
84-35 
