1872.] Weather Prophecies. 433 
definite cause, more or less remotely connected with coming 
changes in the weather. In many country places it is 
common to hear it remarked that “the rain will soon clear 
up, for the birds are singing ;” the coming change is perhaps 
already sensible to their more delicate organisation. There 
is also the appearance of the clouds; and to this indication 
even the lamented Sir John Herschel attached somewhat of 
a reliance, in that ‘“ anvil-shaped clouds” portended a gale 
of wind. But as a rule, the moon may be considered to 
hold the first place of influence upon weather predictions. 
Halos round the moon are the phenomena most commonly 
observed, and are readily explained by the laws of the re- 
flection of light from the particles of aqueous vapour sus- 
pended in the atmosphere. When these halos are coloured, 
we may infer the presence of watery particles in the higher 
regions of the atmosphere; when the halos are white, we 
may conclude that the particles are frozen, and expect cold 
weather. Crossed halos, mock moons, or highly developed 
phenomena, indicate larger crystals of ice, and probably 
frost, hail, snow, or heavy rain after three or four days, 
according to the season of the year. Similarly the laws of 
reflection of light indicate that the cause of a deep purple 
morning or evening sky is the large amount of moisture 
present in the atmosphere. Another effect of the moon, 
when at the full, is to clear the sky of cloud, traceable, says 
Sir John Herschel, to a distinct physical cause, the warmth 
radiated from its highly heated surface; though why the 
effect should not continue for several nights after the full 
remains, in the opinion of the same accurate observer, pro- 
blematic. Other lunar prognostics, founded on arbitrary 
rules, as to the time of the day or night at which the 
changes or quarterings take place, are worse than useless, 
for they are calculated to mislead, and are generally included 
in almanacs or note-books intended for sale only, being in 
some cases attributed to an eminent meteorologist or astro- 
nomer—Sir W. Herschel or others. 
It is of course far from our purpose to enter here into a 
disquisition on the theory of the trade and anti-trade winds, 
and their barometrical indications—subjects that can be 
usefully discussed only in a treatise on meteorology: we 
limit ourselves to the present position of weather prognos- 
tics, although it must be admitted that any advance yet 
made or likely to be made in prognosticating the weather 
arises from the study of such recurrent phenomena, the 
investigation being much aided by the highly developed 
character of the laws of the expansion of gases, upon which 
VOL. Il. (N.S.) gals 
