ON THE LIGHT OF THE MOON AND OF THE PLANET JUPITER. 279 
from glass globes, in the manner already described. It will be noticed that the aperture 
of the object-glass of the telescope has no influence in these experiments, and that no 
correction for its absorption is required, the proportion of light extinguished in pass- 
ing through it being the same in all cases. 
1860, March 26th. A fine clear sky. A few cumuli appeared before the close of 
the experiments. Aperture of object-glass, 5 inches. Focus aperture, 0.0425 ; angu- 
lar diameter at solar focus, 32”.47. 
Telescope directed upon the silvered glass globe B,, diameter 3".436, placed at a dis- 
tance of 1336 feet from the object-glass, in a pearly horizontal line, azimuth 10° east 
of north, and the image of the Sun reflected from it, compared with the lamp S, dia- 
phragm Z. 
h m ft. ft. 
2 1 Sid.time. Bulb to lamp S, 8.17 Bulb to focus, 5.85 
2.9 « e 8.13 « 5.85 
2 15 “ a 8.30 , 5.85 
Lamp 7 exchanged for S, using same diaphragm. 
ft. ft. 
2 25 Sid. time. Bulb to lamp Z 8.30 Bulb to focus, 5.85 
2 29 vi E 8.70 e 5.85 
Telescope directed to southeast side of a white house, at nearly the same distance and 
azimuth. This side of the house receives the direct sunlight at a small angle of 
incidence. 
ft. ft. 
2 43 Sid. time. Bulbtolamp Z 7.73 Bulb to focus, 5.85 
Telescope pointed at the southwest side of the house, on which the direct light of 
the Sun falls at.an angle of about 40°. 
ft. ft. 
2 52 Sid. time. Bulb to lamp Z, 6.17 Bulb to focus, 5.85 
A screen of white paper, painted with “Flake white” and " Chinese white,” was 
placed at the same distance, perpendicular to the sunlight. : 
ft. ft. 
3 2 Sid. time. Bulb to lamp Z, 7.06 Bulb to focus, 5.85 
3 A x s 7.90 T 5.85 
Telescope pointed at a mass of trees without leaves, distant about 1000 feet, and 
180° in azimuth from the Sun. 
SS ft. 
3 20. Sid. time. Bulb to lamp Z, 13.30 Bulb to focus, 5.85 
