go Count Rumford's Account of a Method of 
that the effects of such diminution would become apparent in 
the experiment, were they in reality considerable. 
The following table will shew the results of the experiments 
which were made with a view to determine that fact. 
Experi- 
ments. 
Distance 
of 
the smaller 
Light. 
Distance 
of 
the greater 
Light. 
inches. 
Second dis- 
tance of the 
greater light, 
computed ac- 
cording to 
the assumed 
law of the 
squares of 
the distances 
Difference 
between the 
result of the 
experiment 
and the the- 
ory. 
inches. 
inches. 
inches. 
No. 
No. 
No. 
No. 
No. 
No. 
No. 
No. 
5 - 
6 . 
7 
8 . 
9 - 
10. 
11. 
12 . 
c First dist. 
1 Second dist. 
^ First dist. 
7 Second dist. 
^ First dist. 
7 Second dist. 
^ First dist. 
{ Second dist. 
< First dist. 
7 Second dist. 
< First dist. 
7 Second dist. 
^ First dist. 
7 Second dist. 
^ First dist. 
7 Second dist. 
20 
40 
20 
4 ° 
20 
40 
20 
40 
50 
100 
50 
100 
5 ° 
100 
50 
100 
First dist. 101 
Second dist. 203 
First dist. 100,2 
Second dist. 198,3 
First dist. 100,8 
Second dist. 202,1 
First dist. 101,5 
Second dist. 204 
First dist. 100 
Second dist. 198 
First dist. 95,5 
Second dist. 192,2 
First dist. 95,1 
Second dist. 191,2 
First dist. 96 
Second dist. 192,4! 
202 
200,4 
201,6 
203 
200 
19 1 
190,2 
192 
+ 1 
— 2,1 
+ 0,5 
+ 1 
— 2 
+ 1,2 
+ 1 
+ 0,4 
In the four last experiments, instead of the small lamp above 
described, a common Argand lamp was made use of, the wick 
of which was only drawn out so far as to cause it to emit about 
a part as much light as the other Argand's lamp, burning 
with its greatest brilliancy, which was placed over against it. 
In order that in judging of the equality of the shadows, my 
