218 Chronicles of Science. _ [April, 
With reference to these speculations we must note that inquiries 
specially directed to the subject are required before an opinion can 
be formed. It must be remembered that the moon rises to the 
meridian at a different part of the day in each lunation ; and meteo- 
rologists are familiar with the fact that the hygrometrical state of 
the air varies at different hours of the day. ‘There is the epoch at 
which—on the average—clouds are most numerous; the epochs 
at which the absolute quantity of vapour in the air reaches its maxi- 
mum and minimum; and the epochs (not necessarily the same as 
the preceding) at which the humidity of the air is least or greatest. 
Now we clearly cannot neglect the consideration that the moon’s 
influence—which certainly exists—may vary in different parts of 
each lunation, not for the reasons assigned by Mr. Harrison, but 
because it is exerted at more or less favourable hours of the day. 
And, although we have not space here to explain the considerations 
on which our opinion is founded, there are reasons for anticipating 
that the first and third quarters, when the moon reaches the meri- 
dian in the evening and morning, should be marked by a greater 
apparent influence—one way or the other—than the second quarter 
when the moon reaches the meridian near midnight, a period of the 
day far less critical (as respects hygrometrical conditions) than the 
two former. We may be permitted to question the justice of Mr. 
Harrison’s conclusions, when we find that a marked rise in the tem- 
perature occurs in the middle of that quarter which should exhibit 
(and does exhibit on the average) the lowest temperature. It is 
true Mr. Harrison finds a reason for this, in the supposition that 
fresh cloud may have been found to arise a day or two before the 
third quarter, to supply the increased demand for vapour at that 
period. But when opposite effects can thus be assigned to the 
operation of the dark heat assumed to be emitted from the moon, 
a little uncertainty is thrown over the whole subject. 
As respect the heating of the moon’s surface 1t may be remarked 
that although, undoubtedly, an enormous quantity of heat is poured. 
upon a lunar hemisphere in the course of the long lunar day, yet 
we have no means of knowing how this heat is disposed of. Nearly 
all of it may be at once radiated into space, or a large portion may 
be consumed in effecting changes—as of solids into liquids or of 
liquids into vapours—imperceptible to us, and followed by a return 
to the original state during the long lunar night. It seems hardly 
conceivable that the heat emitted during the latter process of change 
should become in any way sensible to us. Far more probably the 
heat we actually receive from the moon is reflected towards us 
precisely as the moon's light is. 
Messrs. De la Rue, Stewart, and Loewy communicate the 
results of Observations made on Sun-spots, in Kew and in Dessau, 
during the year 1867. Hofrath Schwabe reports that the uniform 
