ON THE LIGHT OF THE MOON AND OF THE PLANET JUPITER. 271 
Albedo of brick-work E. 
Albedo of Jupiter, central element ` 8 ` 
This is not entitled to much confidence for several reasons, but especially on account 
of the difference in color. The side of the house was also strongly illuminated by light 
reflected from surrounding objects, by which its brightness must have been considerably 
increased ; the illumination of the atmosphere intervening would also have a similar 
tendency. Hence it seems probable that the denominator of the fraction expressing the 
relative albedos is too small; the experiment taken in connection with (51) will there- 
fore be in keeping with previous results. 
A distant hill-side of withered grass was not sensibly brighter than the bricks; a 
tract of woodland, without leaves, was darker. The brick was supposed to reflect about 
one fifth as much light as an equal surface of pure white paper. 
1860, March 19. 0* 30” to 1^ 0”, m.s.t. Clear, with haze near horizon. The 
same adjustments and screen-glasses as were used in viewing Jupiter. 
Repeated comparison with brick wall as on 17th. The image seemed slightly more 
intense than that of Jupiter. 
The side of a wooden house, painted white, and by subsequent trial found to be 
barely distinguishable from the purest white paper, gave, 
Albedo of side of white house —— 1 
Albedo of Jupiter, central element 20d SS 
A variety of objects in the landscape, — fields, bare or covered with withered grass, 
trees, rocks, fences, &c.,— in the azimuth opposite to the Sun's, and again nearly in the 
same azimuth with it, gave, 
Albedo of landscape — 1- 
Albedo of Jupiter 8 
1860, March 23d. qn m. s. t Sky perfectly clear, — between cumuli. Adjust- 
ments, spite, &c., as usual, but the aperture of the object-glass was reduced until 
the objects viewed through the colored screens were judged to have less brightness 
than J upiter. From five trials, after applying the proper corrections, I find, 
Albedo of side of white white house _ e "s 
Albedo of Jupiter, or, central element ^ 2.1 
A sheet of white paper placed against the side of the house was found to be a good 
match in point of brightness. A disc of chalk, ground flat and painted with “ Flake 
white,” was, however, sensibly whiter. 
VOL. VIII. 36 
