86 Count Rumford's Account of a Method of 
merely in consequence of the divergency of the rays ; and as it 
is more than probable that air, even in its purest state, is far 
from being perfectly transparent. 
For greater perspicuity I shall arrange all my experiments 
and inquiries under general heads, and shall begin by prefixing 
to those which relate to the subject now under consideration, 
the general title of 
Experiments upon the Resistance of the Air to Light. 
EXPERIMENT I. 
Two equal wax-candles, well trimmed, and which were 
found by a previous experiment to burn with exactly the same 
degree of brightness, were placed together , on one side, before 
the photometer, and their united light was counterbalanced by 
the light of an Argand's lamp, well trimmed, and burning 
very equally, placed on the other side over against them. 
The lamp was placed at the distance of 100 inches from the 
field of the photometer, and it was found that the two burn- 
ing candles (which were placed as near together as possible, 
without their flames affecting each other by the currents of 
air they produced), were just able to counterbalance the light 
of the lamp at the field of the photometer, when they were 
placed at the distance of 60,8 inches from that field. One of 
the candles being now taken away and extinguished, the other 
was brought nearer to the field of the instrument, till its light 
was found to be just able, singly, to counterbalance the light 
of the lamp ; and this was found to happen when it had 
arrived at the distance of 43>4< inches. 
