Edgefield advertiser. [volume] (Edgefield, S.C.) 1836-current, 1839-05-30
Miscellaneous.
From the Pennsyiranian.
THEORY OF RAIN.

Mr.. Espy, in letter published IN the Ma
tional Gazette, gives the following account
of the mode i. which he thinks be can pro-
duce rain by artificial means:
Firsi-It Is wnby experiment,that if
air should be expanded iuto double the
volume by diminished pressure, it would
be COO Il about ~ degrees Fahrenheit.
Second-I have shown by experiment
hat if air at The common dew point in the
summer season in time OF drought, II de-
srees, should go up in column TO height
sufficient to expand it by diminished pre-
sure, INTO double tile volume, it would con
dense into walter or visible cloud. by The
cold expansion, more than one half OF ITS
vapor-a quantity sufficient to produce
nearly three inches Ot rain.
Third---lt is known by chemical princi-
pies, that the caluric OF elasticity given out
during the condensation of this vapur,
would be equal tu 81, ,UOO tons OF anthracite
coal burnt on each square nile, over which
the cloud extended.
FOURTH have shown by experimcn,
Isee Sat. Courier, March lS, 1887 that
this caloric of elasticity would prevent the
air from cooling only about half as much
as it would, if it had no vapor in it, or
abou, As degrees at the height assumed,
which would, cause the air in the cloud TO
be, at that height, about IS degrees war
mer than the air on the outside Of The cloud
a, the same height. have shown from
these principles see Journal of the Frank
lin Institute for 1886 that The barometer
would fall under the cloud thus formed, in
favorable circumstances, quantity as
great as it is known TO fall sometimes un-
der the middle Of dense and lofty cloud,
and that consequently the air would rush
on all sides towards the centre of the cloud
and upwards in the middle, aud thus con-
tinue lhe condensation of the vapor aud
the formation Of cloud and the generation
OF rain. See also The Journal oflhe Frank
I'm institute for September and October,
1888 and for January, February and
March, and subsequent, 1889.
Fifth have shown also in the VOL
umes quoted above, that the air does move
inwards on all sides towards the centre Of
the space or region where a great rain is
falling, and O: course upwards, after it
comes in u.nlerlhe cloud, which is 50 much
lighter than the surrounding air; at least,
that il does so in all storms which have
been investigated, which now amount 10
sixteen, besides several lornadoPs, in all Of
which The trees were thrown with tops in-
wards.
From the principles here established by
experiment, and afterwards confirmed by
observation, it follows that if Il large body
of air is made to ascend in column, Il
large cloud will be generated, and that the
cloud will contain in ITSELF self-sustainiug
power which may move from the place
over which il was formed, and cause the
air over which itpasses to rise up into it,
and thus form more clouds and rain, until
the rain may become general: for many
storms commence in the West Indies, very
narrow, are known to move from the place
OF beginning several thousand miles, wide
ming out and increasing III size until they
become many hundred miles wide. See
Bedfeld and Reid; and the Reports of
joiul Committee.
Ii these principles are just, it will follow
when the air is in favorable state. that
the bursting out of a volcano ought TO pro-
duce rain; and such is known TO be The fact;
and | have abundant documents in my
posseSsession to proveit.
So under eery favorable circumstances
the bursting ou, of great fires ought 10 pro-
duce rain; and I have many facls in my
possession rendering it highly probable, if
not certain, that great rains have sometimes
been produced by great fires.
If | should be encouraged TO 60 on With
the experiment, mean 10 have a large
mass OF combuslibles prepared ready for
use, and when have found all the cir
cum>tances mentioned before, favorable in
a time of drought, would set lire to the
circumference in various places at once
Soon after the fire commences, / will cx
pect TO see clouds begin to form, about as
many hundred yards high as the tcInpcra-
ture of air is above the dew-point. in de-
grecs of Fahrenheit. will expect to see
this cloud rapidly increase in size, it its
top is not swept of by acurrenl Of air. at
a considerable distance above The earth
until it becomes so lofty as TO rain. shall
expect the cloud 10 move eastwardly, in-
creasing in width as i. advances, and the
next day shall expect the region to the
south Of where the rain fell, TO be visited
by rain; for reason explained in my wri-
lings.
From the Louisianian.