294 COMPARISON OF THE LIGHT OF THE SUN AND MOON. 
The image of the Drummond light compared with the image of the Sun, both re- 
flected from a silvered globe, has a strong golden-yellow hue. The * Bengola light” 
answers much better. It shows, however, a decided tinge of pink when brought side 
by side with the pure white of the solar image. At night it is of an intense white, 
with a bluish glare; but when contrasted with the Moon's image it exhibits a strik- 
ing similarity in quality of light, with only the very slightest cast of pink at times sus- 
pected, of the same character with that noticed in the experiments on the Sun, but no 
trace of the blue can then be detected. It seems, then, that in point of color the 
light of the Sun and that of the Moon are very nearly similar. 
The first experiments for determining the ratio of sunlight to moonlight had refer- 
ence to their chemical intensities, and gave the proportion, | 
ee eat of E de eic 240 000. 
Chemical intensity of moonlight 
The reader is referred to the Memoir preceding for a more detailed statement. 
By diminishing the aperture of the object-glass of the 23-foot refractor until a circu- 
lar area of only 0'.021 diameter was exposed, and viewing a small portion of the Sun's 
disc, subtending a diameter of 32”.47, the intensity was estimated to be equal to that 
of an equal disc of Jupiter seen with an aperture of 14".94; the eye having been 
guarded from exposure to daylight, and its judgment assisted by different combinations 
of colored screens used alternately upon both objects. After applying the necessary 
reductions for atmospheric extinction, for the distribution of light over the discs of 
the two bodies, and other conditions which need not be explained in detail, as the 
experiment can be at best but a rude essay, we obtain the value, 
Sunlight 
POPE E —— == 927 000 000 
Light of Jupiter at mean opposition > 
from which, by using, as above, 6430 for the ratio of the light of the full Moon to 
Jupiter, we deduce 
S = 144 000. 
A second method employed was to place a silvered glass globe at a distance of about 
one fourth of a mile, and to compare the image of the Sun reflected from it, and seen 
with a telescope from a darkened room, with a small disc of the flame of a Carcel 
lamp; this was subsequently referred to the light of Jupiter and the Moon, seen with 
the same telescope. The result furnished the value, 
S = 375 600. 
