ON THE LIGHT OF THE MOON AND OF THE PLANET JUPITER. 281 
1860, April 7th. Clear. Aperture of object-glass 14".94. Compared image of Sun 
reflected from B,, distant as before, 1336 feet, with lamp J, diaphragms Z, M, and X. 
hm ft. ft. 
14 Sid.time. Bulb to lamp Z, diaphragm Z, 6.90 Bulb to focus, 5.85 
Chalk-ball, G, painted pure flake-white, diameter 17,614, exposed in same position 
to sunlight. It showed a phase like that of the Moon three days from full. 
ft. ft. 
Bulb to lamp J diaphragm Z, 9.85 Bulb to focus, 5.85 
Lamp diaphragm altered to M. 
ft. : ft, 
Bulb to lamp J, diaphragm M, 9.60 Bulb to focus, 5.85 
Silvered globe B, in same position. 
ft. ft. 
Bulb to lamp Z, diaphragm M, 6.50 Bulb to focus, 5.85 
Lamp diaphragm altered to X. 
y pom» ft. 
Bulb to lamp Z, diaphragm X, 20.4 Bulb to focus, 5.85 
159. Sid: time. « a 20.1 « 5.85 
After applying the necessary corrections, we have the following for the results of the 
comparisons made by means of the lamps. 
1860, March 26th. Southeast side of white house on which direct sunlight falls at 
small incidence. The same correction has been applied to reduce to direct illumination 
by sunlight at perpendicular incidence, that was used on March 23d. 
Albedo of house _ 1 : 1 Obs. 
Albedo of Jupiter ` 2.3. 
Southwest side of house. Angle of incidence of sunlight, 40°, 
Albedo of house = 1 Obs. 
1 
Albedo of Jupiter 1.5 a 
White paper screen. Angle of incidence of sunlight, 90°. 
Albedo of white paper ` 1 2 Obs. 
— 
Albedo of Jupiter 2.0’ 
* 
