OF HEAT FROM THE MOON. 
613 
of each day varies directly as the square root* of the number of sets, and inversely as 
the reduction to the zenith, October 4th having only half weight on account of bad 
weather. 
Observations without glass plate. 
1870. 
Speculum-factor. 
Weight. 
Aug. 8 
. . 1-806 
0-9677 
’ 10 . 
. . 1-560 
0-8982 
11 . 
. . 1-530 
1-2170 
12 . 
. . 1-298 
1-4270 
13 . 
. . 1-456 
1-5620 
14 . 
. . 1-046 
1-3010 
15 . 
. . 1-185 
1-4330 
16 . 
. . 1-140 
1-4940 
19 . 
. . 1-314 
1-5190 
Whence August speculum-factor v 
without glass plat< 
3 = 1-345; weight 11-82. 
In the same way : — 
1870. 
Speculum-factor. 
Weight. 
Oct. 4 
. . 1-090 
0-5645 
„ 9 . . 
. . 0-822 
1-7360 
„ io . . 
. . 0-833 
1-4880 
Whence October speculum-factor without glass plate = 0-866 ; weight 3*79 f. 
These factors may also be deduced, though with less certainty, from the experiments 
with the glass plate for those elongations within 
the range of the observations of 
1871-72. 
1870. 
Speculum-factor. 
Weight. 
Aug. 8 . . 
. . 1-818 
0-5386 
„ io . . 
. . 1-300 
0-6351 
„ 11 • • 
. . 1-030 
0-9970 
„ 12 . . 
. . 0-880 
1-0740 
Whence August speculum-factor with glass plate = 
1-164; weight 3 "2 4. 
In the same way: — 
1870. 
Speculum-factor. 
Weight. 
Oct. 4 . . 
. . 1-042 
0-4837 
„ 9 . . 
. . 0-722 
1-1801 
„ 10 . . 
. . 0-661 
1-0868 
Whence October speculum-factor with glass plate =0-867 ; weight 2-75. 
These four factors must be kept separate, because in 1870 the glass plate was always 
* This ratio was used as tending to lessen the preponderance of any given day. 
t Combining the factors for experiments without glass plate, it appears that a new speculum reflects 1-55, 
say once and a half as much heat as the most tarnished one that would be considered serviceable. 
4 n 2 
