EVIDENCE OF LUNAR INFLUENCE ON TEMPERATURE. 253 
minima only before the day of change. The just expectation would be 
about 3 maxima and 3 minima for the whole period of seven days. 
The results at Dublin for twenty-two years were at— 
)p. 
a 
In this case also minima precede the day of the change. 
For the rest more than half of the whole number of the superior maxima 
and minima occurred on the following eight days, both at Greenwich and 
Dublin, viz the third day before, and the third day after @ ; the second day 
before, and the second day after ) ; the day before ¢ ; and the days on 
which the moon entered on her first, second, and third quarters. 
Of the six days of the lunation on which no superior maxima or minima 
occurred, either at Greenwich or Dublin, three were found at @, two at O, 
and one at ¢. 
Many other details of interest might be enumerated; but when it was 
considered that the observations on which they depend are ordinary daily 
means, taken irrespective of the hour of the moon’s changes, it seemed 
hardly worth while to dwell on minute points which would at present only 
complicate the question. 
7. The dissolution of clouds in presence of QO, first announced as a 
meteorological fact by Sir John Herschel, has since been confirmed by 
observations made by Mr. Piazzi Smyth on the Peak of Teneriffe, at which 
altitude sufficient heat was detected in the lunar rays to make it possible that 
evaporation might cause the phenomenon in still higher regions of the air. 
_ It had been noticed previously, and independently, by Baron Humboldt in 
America. 
a A still more remarkable fact has been noticed by Mr. M. J. Johnson, the 
Radcliffe Observer at Oxford, viz. that the cloud-dispelling power of the moon 
extends beyond the period of 0; or as it would perhaps be more correct 
for me to say, is not confined to it. From repeated observations it appears 
that at Oxford the influence begins after the moon is four or five days old, 
and lasts till she approaches the sun again the same distance on the other side. 
So frequently had this been noticed by Mr. Johnson, that during a course 
of observations on which he was engaged a few years ago, he felt that his 
attendance at the observatory could not be dispensed with, however unpro- 
“mising might be the appearance of the night, until the moon had fairly risen ; 
and over and over again when this has occurred, the sky, before com- 
pletely obscured, has become clear. . 
Mr. Johnson has furnished me with a comparative statement of the number 
of observations of the sun and moon taken beween the day of ) and the day 
after O, in the years 1844, 1845, and 1846, which shows that the moon was 
_ Visible on an average 137 times on the meridian, while the sun is seen only 
_ 100 times. In the year 1844 the preponderance in favour of the visibility 
of the moon was as 1°52:1. 
____ Aclearing of the atmosphere, to whatever attributable, by increasing solar 
__as well as terrestrial radiation, and so producing extremes of heat and cold, 
would, it is evident, be sufficient to account for some of the results enume- 
rated in this communication. 
_ The importance of Mr. Johnson’s facts, in connexion with the peculiar 
_ action which it has been shown exists at the period of ), will beat once ap- 
" parent; and however little required, the latter in a measure strengthens the 
probability that the effects which have been observed are not accidental. 
