296 ‘COMPARISON OF THE LIGHT OF THE SUN AND MOON. 
dimensions placed at a distance from it, under angles of incidence differing by large 
amounts; only when the reflected image was viewed from a position which brought it 
nearly into a line with the Sun, was there any noticeable change of brightness, and this 
was easily accounted for by the well-known fact, that the reflective power of a surface 
not perfectly polished is greatest when the angle of incidence is least. This extreme 
position, however, was not approached when the comparisons between the Sun and 
Moon were made. 
From the above, after applying small corrections for atmospheric extinction, and to 
refer the sunlight to its amount corresponding to the mean distance of the Earth from 
the Sun, we have 
Bengola 
Log. == 9.801 uly Ist. 
E Suns image in Ð; : n ee 
& s 9.786 © 14th, 
Adopted, 9.793 
The next step was to compare, in precisely the same way, the image of the Moon 
reflected from the globe B; with the Bengolas; this was effected on July 31st, the 
Moon being nearly full. 
1860, July 31. Sky fine and perfectly clear. 
Globe B; in open air exposed to moonlight, and the reflected image compared with 
single Bengolas in the same way as had been done with the Sun. 
Gy 1815 Bid duo Bengola to Globe Py == 988. een OE MOE Or Pe P x 1.65 
tometer Globe, 
(b) BE “ ` 1689 « 2.48 
(e) 30 « ` ` 1682 ` 2.08 
(d) Ho « ` 1718 « 2.98 
i nw h “ « 1718 « 2.53 
Cf) ccu s ` 1718 « 2.84 
The following corrections must be applied to reduce the comparisons to the bright- 
ness of the full Moon in the zenith, and at its mean distance from the Earth and from 
the Sun. : 
For atmospheric extinction: — 
Comparison (a), i . Log. correction = 0.174 
e | (b, (e), ` PI z 0.148 
tou (Dee (E e 0499. 
