The New York herald., 1873-12-27
LIBERAL CLUB.

Artificial Production OF Rnin-Lecture
by Mr.. Edward Powers. kN
Mr.. Edward Powers, q well known civil engineer
OF Chicago, delivered lecture last night at Plimp-
ton Hall, before the Liberal Club, on "Artificial
Production Of RAIN" The following are the main
conclusions Of the speaKer:- I gss essssf
He has examined a large number OF cases or rain
following battles, from which he deduces the fol-
lowing approximate conclusions, viz. That all
great battles IN which much artillery Is used are
followed very soon by rain. That about 90 per
cent Of oil battles and bombardments or import
ance are followed BY rain within the hrst 4S hours
about 80 per cent are followed within the firss
"a hours; whereas, on an average, only 80 per
the battles had no influence in bringing It. this
percentage being calculated from the average
ns'r ss4s are S 1sny re- Dass ass Il h the ans p 5
tina. rains following t1ie' other engage sss
fought In ial and winter as well as in spring and
season in Mexico, "a well as 10 the United States
and Europe. That heavy rain follows great battles
fought IN time OF drought and that the rams ol-
thunder ana lightning. Mr.. Power in stating
the above conclusions, gave many interesting facts
for the assumed production OF rain by battles or
artillery firing, may be briefly stated as foows:--
Is caused by the union OF two bodies cir, OF
which Is warmer than the other, and both satu-
OF air are mixed together they cannot, when
mixed, contain as much vapor as they
did before. This fol ows from the principle that
warm air Is capable OF containing more vapor than
cold air, and tuat its capacity for vapor increases
and dminishes 10 much greater ratio than the
temperature. Now, there must be currents Of
warm air saturated with vapor IN the atmosphere
above US, for the trade winds take up vast quantI
ties OF vapor from the ocean, which vapOr Is car
ried northward and southwark by the great ,equa-
tOral currents. Hence In explaining how artil.
lery ring brings rain 1t s only necessary to snow
how 1t can cause such . current TO mix with the
which is original with himself, is that 1t does
so by rarllyinR the AIR in the humid cur
rent, thus causing 1t to. rise. 1t rariies
aqueous vapor which it contains. 1t condenses
this small amount of vapor by cOncussion, which
rs similar IN its action TO sudden pressure, and we
know that by pressure aqueous vapOr Is condensed
and Its latent neat evolved. When artillery firing
brings rain there is, in other words, condensation
Of vapor in two ways-hrst, very small amount
caused BY the mingline Of the humid current with
amount or condensation leads to the second aud
greater condensatlon, because the larent heat
the humid current and causes it to Use.
AS the air currents must be very extensive,
being perhaps thousands OF ieet in thickness, 1T
viii take little time, alter such current las been
rarfed by conclusion. ior 1t to into the colder
current above 1t, and. III the meantime TINS por-
ton OF the current would pass on, we could not
expect that the rain would commence at the place
where the firing takes place. The fact that the
battle field Is generally included In its area. how
ever. shows that after commencing 1t works back
on the path OF the current.
Mr. Powers thinks that some experiments ought
to be made TO determine II we cannot as well pro-
duce those motions III the upper air which lead to
ram as to watch for their production by natural
causes and foreten their approach, AS Is now done
by the signal service OF the army.
A lively discussion ensued after the reading or
this lecture, alter which the meeting rendered
vote OF thanks TO Mr.. Powers and adjourned.