AND ON A SIMPLE PHOTOMETER. 367 
Now, let us imagine this stratum to be transferred to the surface of the sun. 
It would there be spread over 46,275 times less area; consequently, its thickness 
would be increased that number of times, and would therefore amount to about 
1132 inches, or about 94 feet, embracing 138,825 layers of flame, equal in bright- 
ness to an electric light of the above-mentioned intensity, and it would at its 
outer surface possess a brilliancy equal to that of the surface of the sun. 
| It is evident, however, that there might be a very considerable addition made 
_ to the thickness of such a stratum, without affecting, in any appreciable degree, 
its proportion to the planetary distances. If then, the thickness of the stratum 
_-were increased 520 times, making it 49,000 feet, then it might embrace 72,000,000 
 Jayers. each of them having an individual brilliancy not greater than that of a 
~ wax candle. The real thickness of the stratum in which the luminous property 
of the sun resides, may be very considerably greater than the above estimate, 
_ which is somewhat over 9 miles; and the luminosity of each individual film com- 
; posing the stratum may be very considerably less, without affecting the general 
result. 
VOL. XXTI. PART III. oG 
