Evening capital. (Annapolis, Md.) 1884-1910, 1891-05-19
ANNAPOLIS, MD, TUESDAY EVENING. NAY 10, 1891



is belief which has been slowly grow
ing out OF unscientific observations and
confused recollections of the state of the
weather before, during, and after battles.
Among soldiers there is general inn
preston that the noodgates of the heav-
ems were opened shortly after each en-
gagement in which they took part, and
from them the idea las spread that the
roar of guns shakes the atmosphere and
precipitates the water in it.
OF late men of scientific training nave
come to attach sol..e importance to this
belief, and Congress was induced to APP
propriate e., 900 for making experiments
under the direction of the Department of
Agriculture. This was done largely at
the instigation of Senator Charles Farwell,
of Illinois, who was greatly impressed by
q book published by Edward Powers,
civil engineer of Dolavan, Wis.
In this little volume, entitled, @War
and the Weather, Mr.. Powers has
gathered such data as were accessible in
current histories. They are by no means
complete, the atmospheric conditions
being mentioned by the writers of ac-
counts of battles only casually and with
no thought of their scientific value. The
records on the logbooks of gunboats and
warships engaged in the late rebellion
furnish valuable material, but even this
is too fragmentary to be conclusive. The
facts brought tot ther form, however,
strong presumptive evidence that rain
does, as a rule, follow extensive gum
powder explosions.
Rain fell early on the day after the
FIRST Bull Run, in July, 1851, and the en-
gagements in West Virginia during the
same month, by which Mcclellan made
the reputation which secured him tho
command of the army of the Potomac,
were all followed by violent downpours.
The peninsular campaign in the following
year, which ended with the battle of
Malvern Hill, was a succession of can
nonading and of rain. The second Bull
Run, Chantilly, Antietam, Fredericks-
burg, ChancellorsS lille, Gettysburg, and
the Wilderness engagements were all fol-
lowed by rain, as were likewise the great
conflicts in the West and the lombard
ments along the coasts.
That it did rain after each battle is, of
course, not proof positive that the firing
brought on the rain; but it decidedly
lends color to the theory that the two
had some connection. The proof would
be stronger did we know in each case
what the condition of the atmosphere was
before the firing began or what were the
chances under ordinary circumstances of
rain falling. The days on which the bat
ties were begun seem to have been bright
and clear, but although the weather has
a tendency to perpetuate itsslf-the
probabilities of its being on one day what
it was the day before being stronger than
that it will be different--it does not fol-
low that the change to rain would not
have come anyhow.
If Mr.. Powers's statments about the
weather prevailing at some of the battles
of our war with Mexico are correct, that
war furnishes; perhaps, the strongest evil
dence in favor of his theory. He says
that for months before the battle of
Buena Vista, and for months thereafter,
no rain fell in that region, it being the
dry season, while showers were notable
all through the second and last days
fighting. At Monterey the cannonading
was carried on during dry month and
was followed by rain also, as were sew
eral other engagements at the same
periodic of the year. Here, if the facts are
as stated, no rain was expected for long
period thereafter, but rain came directly
after artillery reverberations had ceased.
The theory that rain can be made to
fall by exploding gunpowder in large
quantities rests to some extent on Profes-
sor Maury's conclusion that the principal
portion of the aqueous vapor falling in
the United States is brought by atmos-
pheric currents from the Pacific Ocean.
In petition presented to Congress some
time ago for an appropriation to defray
the cost of experiments Mr.. Powers says
that it is contended that the great south
east trade wind of the Pacific, which
meets the northeast trade wind near the
equator, after rising there, flows over
that trade wind to the belt of calms near
the Tropic of Cancer, where it descends
and becomes great southwest rain bear
ing current above the United States, ex-
tending from the surface of the ocean, it
is supposed, to height of about three
miles, This current, it is argued, blows
over the Pacific for about 2, 900 miles and
takes up enough water in the form of va
por during the year to depress the whole
surface of the ocean 8 or 10 feet. Some
of it falls back into the ocean, but the
bulk of it is supposed to be carried over
the continent, to the Atlantic, to north
ern Europe, and the Polar regions.
This view was confirmed by the obeer-
vations of the United States Signal Serv-
ice to this extent that nearly all the great
storms come from the west or the south
west. Balloonists likewise are agreed
that there is a constant current running
to the east over this continent.
1t follows from this that If there is any
thing in the belief that cannonading
causes rain the rain must fall either from
directly overhead or to the east of the
place of firing, and never to the west.
On this point nothing ID, however, def
nitely known. Rain is Of course the re-
suit of condensation. The vapor viii
continue to float in the air until it meets
a colder stratum, when it is forced to-
gether into drops that are too heavy to
be held in suspension, and then they fall
to the ground.
How artillery firing is to produce the
cold necessary to condense the watery
vapor into rain is not so clear. Suppose,
however, that above the warm equatorial
r.~..~.4 .1or~x.1 ..vsf1, x.,~sofs.ro frnrra fi.o