ON THE LIGHT OF THE MOON AND OF THE PLANET JUPITER. 211 
distinguished on the bulb, when placed at the distance of two or three feet from the 
focus. | 
Removed focus diaphragm and returned to Jupiter without altering lamp. 
9 46 Sid. time. Jupiter. Bulb to focus, 2.60 To lamp, 21.70 
$4: cR e Tis 2.90 “ 21.70 
5 x 55. 3 & s 1.24 > 10.74 
10 0 = = E 1.50 w 10.96 
la oe: 4 « 145 « — 1100 
.1860, April 2d. . Quite clear. No clouds seen through the evening. Moon 23 days 
from full (v — iras For J upiter, the focal image, without diaphragm, was used. 
p En D. 
9 7 . Sid. time. Jupiter. Bulb to focus, 9.45. To lamp £ Diaphragm Z.. 20.60 
9 99 2 « & 5.25 Soh " X. Sa 
t oi EE C ON LS 5.95 PI v eg 4890 
Jn. Ca ee 5.80 Bt g SW 28.90 
$48 po d « 6.05 r.i VN. 347 
109 e edt: e 6.95 «  R. “ 'M. 24.60 
ak 4 ew «c 5.80 « 5 * — M, 20.60 
"3039  —* (e « 5.10 KE x “ M. 21.80 
mule c E (4 5.55 " c, * — M. 925.60 
Set upon “Moon. : Focus | diaphragm 32" 47. 
bh. i EE brightest in south- ft. A ft. 
10 47. Sid. time. is gon briatas P San's $ Bulb to focus, 5.80 Tolamp W. Diaphragm M. 12.70 
s o E “alt. =.60% . 
Centre of Mare Ti nquillitatis, 
n a line ati Crater 
; Maskelyne and the Mare Crisi- ; 
10:54. e: um. un'salt.859. This is p « 6.20 & W. D M. 19.70 
the darkest part of the Moon, 
upon which the Sun is shin- 
ing ata high altitude. 
Sun's alt. 75°. 
KS iun Mes Das 7 6.20 “« W. " — M, 17.20 
quillitatis. 
The. first series, March 2d, gives ‘the relative quantity of light transmitted to the 
Earth from a circular area of J upiter, 32".47 in diameter, compared with the light from 
areas subtending. the same angle, taken from different parts of the Moon. This pro- 
portion for the brighter regions of the Moon, on which the Sun is shining at a high 
altitude, is 
cB : y 49 
Wi - gl 
