432 PEOCEEDINGS OF THE SCIENTIFIC ASSOCIATION. 
earth a portion of its heat, in the same manner that it 
reflects the sun’s light, although in a much inferior and 
more feeble degree. The clouds, which are nothing ruoro 
than the vapour of water in a semi- condensed state, receive 
this reflected heat, The heat thus transmitted to the 
clouds will cause them to pass from the state of cloudy va- 
pour to that of transparent and invisible vapour, which, 
indeed, is the general condition of the great mass of aque- 
ous vapour which the sun is perpetually raising from the 
oceans and seas. This transparent vapour is of course 
imperceptible to our senses. It remains on high com- 
mingled with the air until when acted upon by a colder 
stratum of the atmosphere, it again resumes the condition 
of cloud, , and finally descends in the state of rain to bless 
and fertilise the earth. 
Now, here we have a specified effect assigned to a spe- 
cified and sufficient cause. There is no conjecture in the 
matter. We do not say, however, that this tendency to 
clear the sky of clouds by the reflected heat of the full 
moon will invariably take effect. The clouds may be so 
dense, and so nearly approaching to the condition of rain, 
as to be insusceptible of the very weak influence of the 
reflected lunar heat. But although the effect that we have 
described cannot be reckoned upon with positive certainty, 
yet if any one will take the trouble to put down in his 
pocket-book an impartial and fair record of the state of the 
sky as to clouds on the night preceding each full moon, 
on the night of the full noon, and on the night after — 
from an hour before the moon rises, and thence hourly, as 
late as his convenience will allow — ho will find after a 
twelvemonths’ observations a large preponderance ef in- 
stances where the clouds were dissipated on the full moon’s 
appearance in the manner we haye mentioned. 
