OP 1IPAT PROM THE MOON. 
619 
It will be remembered that the value <pz = 0-0046 for 2 = 29° was obtained by com- 
parison with Seidel’s results, based on the comparison of observations of the light of 
stars near the zenith with that of others at various altitudes. 
Formula (1) now enables us to find this quantity independently of Seidel’s results ; 
for since <pz is the logarithmic factor for reducing to the zenith it must become zero for 
g = l, or we have the new condition 
log a 4- logyj=0 ; 
it is, however, 0-00858, which must be added to all the values of <pz and subtracted from 
log a in order to fulfil the above condition. 
Simultaneous Observations of the Moons Heat and Light during the Eclipse of November 
Uth , 1872. 
During the partial eclipse of the moon of November 14th, 1872, an attempt was made 
to ascertain whether or not the lunar surface required an appreciable time to acquire 
the temperature due to the action of the sun’s light shining on it at the moment. 
Obviously a total eclipse would be a favourable time for determining this point (at 
least for heat which has penetrated to a small depth only), as the transition from light 
to darkness is so much more rapid than that caused by the moon’s rotation on her 
axis ; but owing to the smallness of the eclipse (there being little more obscuration than 
that due to the penumbra alone), the considerable decrease of the moon’s altitude 
towards the close of the eclipse, and still more to the uncertainty of the weather (which 
allowed us only a few glimpses now and again of the moon), the results only go so far as 
to show that the heat was diminished during the eclipse in a rather greater proportion 
than the light. The minimum for both heat and light occurred at or very near the 
middle of the eclipse. 
The following Tables, in which the columns correspond respectively to those with 
the same heading in the Tables already given, contain full particulars of the observations 
and their reductions. 
The moon’s light was measured with a Zollxer’s photometer, with which, as is well 
known, the total light of the observed body is, coeteris paribus, proportional to the square 
of the sine of the reading of the intensity-circle. This reading is given in column I. (see 
next page). This being borne in mind, the meaning of the other columns will be readily 
understood. 
Observations of the Moon’s Heat, Nov. 14th, 1872. 
Mean deviation 
(G). 
The Moon’s 
Sidereal time. 
s. 
Zenith- 
distance. 
Apparent 
semidiameter. 
log (£)■ 
log (ff). 
$z. 
Zenith-mean (.?). 
h m 
6 15 
479-0 
o 
2 
7 
50-2 
15 40-0 
9-9960 
0-9970 
0-0426 
520-0 
7 47 
264-7 
-i 
40 
62-4 
15 37-5 
9-9977 
0-9994 
0-0906 
323-9 
8 32 
186-4 
+i 
34 
68-9 
15 35-7 
9-9994 
0-0010 
0-1439 
259-8 
8 45 
182-5 
+i 
34 
70-8 
15 35-2 
9-9994 
0-0014 
0-1649 
267-3 
9 6 
198-6 
+i 
32 
73-9 
15 34-4 
9-9993 
0-0022 
0-2059 
320-2 
The moon’s tabular semidiameter . . . =15 36-6 
The moon’s adopted apparent semidiameter =15 30-0 
MDCCCLXXIII. 4 O 
