The Indiana State sentinel., 1874-02-03
BRINGING DOWN RAIN.

SHOOT FOR 1T WITH CANNoN-How THE
WASTE PLACES OF THE EARTH NAY BE RE-
CLAIMED. aef rt.rH
Professor Edward Powers, of Chicago, is
engaged in endeavoring to demonstrate the
practicsbility of controlling and distributing
rainfall by means of concussions produced
by the firing of artillery. The New York
Herald gives a summary of his
lecture in their city: The average length
of time between the commencement of the
heavy firing and the beginning of rain is 26]z
hours. Rain following great battles in which
much artillery is used is almost always very
heavy Engagements other than great bat
ties, in which much artillery is used, are
also generally followed by heavy
rain. but musketry firing does not
bring much rain. Rains follow battles not
only in the spring and summer, but also in
autumn and winter. Rains follsw battles
not only in this country and in Europe, but
in the dry season in Mexico. Heavy rains fol-
low great battles fought in time Of drought.
The rains following battles are generally
accompanied with thunder and lightning.
| The theory of rain generally accepted by
philosophers is that It is produced bv the
union of two bodies of air, one of which is
colder than the other, and both saturated
with aqueous vapor. 1t has been proven by
xperiments than when two such bodies of
air are mixed they cannot, when mixed,
contain as much vapor as they did before,
the reason for which is explained by the
principle that warm air has a greater
capacity for vapor than cold air, and
that this capacity diminiShes in
much greater ratio than the temperature.
Now, the trade winds take up large quanti-
| ties of vapor from the ocean, which vapOr is
| is carried north and and south by the
equatorial currents. Hence there are gen.
orally above Us currents of warm
| air saturated with vapor. To ex-
plain how cannon firing produces rain,
| it is only necessary to explain how these
currents are caused to mix with the colder
currents above them. The exclamation is
that it does so by purifying the humid cur
rent. 1t rarifies it by condensing a small
portion of the vapor which it contains. 1t
condenses this small amount OF vapor by
conclusion, which is similar to
SUDDEN PRESSURE,
And we know that by pressure aqueous
vapor is condensed and its latent heat is
given out-thatis, when cannon firing brings
rain, there5s condensation of vapor in two
ways: first, little condensation by the
pressure of the shocks of concussion,
which causes an evolution of heat and
ratification of the air; apd second,
great condensation caused by the rise of the
humid current and it's mixing with the
colder one above IL. AS IL Will naturally
| take little time for an air current hundreds
and perhaps thousands of feet in thickness
| to rise into the colder current after
being rarified by the conclusions, and
as, in the meantime, the air so
rarified will be carried along by the current,
it follows that the rain will not commence at
the place where the firing takes plaee. 1t
will generally work back to that
place in the path of thu current,
however, arriving, as before stated, IN an
average time OF twenty six and ons-half
hours from The commencement OF the
| firing. Unless the firing is hesSy and con-
tinued for two or three hours, so as to rarify
| larger area ana volume Of the air current
as it passes over, there will be no rain, or if
there is rain somewhere on the path Of the
air current it will not reach the place where
the firing takes place, as the equilibrium be-
tween the two currents will be res.ored
before the rain reaches that point
Battles followed by heavy rain are: First.
Bull Run, Fair Oaks, Pittsburg Landing (or
Shiloh), Malvern Hill. Second Bull Run,
Stone River, fredericksburg, Chance lors-
vile, Gettysburg, Spottsylvania Court
House, Cold HarbOr, Nashville. During the
second day of the battle of BIena
Vista. Mexico, there were two vi0lent
showers, though this was in the dry
season, and it had not rained before AMI did
not rain after for several months. Would it
! not be metamorphosis for which the world
might be thankful if cannon could become
| implements of agriculture instead of remain
ing destroyers OF life?