New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1891-07-29
RAIN FOR THE ARID REGIONS.

The only attempts TO produce rain artificlally
which deserve serious attention just now are
those conducted. or about to be conducted. by
General Dyrenforth under Government au-
spices Before many weeks, possibly within O. le"
days, the public may learn something OF eie
result of his experiments, which, 1t Is Dehe'c"
from unofficial information, are being trieu -
Western Texas, near Midlsnds. Nature re"aruo
persistent investigation, sometimes WIN ou0n
happy surprises that it would be rash, al presenV
to venture any decided opinion as 10 uno ouo
como of this interesting test. 1t is in order' now
ever, to mention some of the considerations winch
enter into the question.
The heaviest natural rainfall occurs IN those
parts of the globe where afr heavily laden "ioh
vapor-and il will carry the more the warmer
it isis in some manner greatly cooled TWO staUolS
famous in this regard are Mahabeshwar ana
Cberanunie in India The summer monsoon
there is a hot, very moist. tropical wind, drawn
in from the Indian Ocean, and forced up
ward by contact with mountains little way
inland Thus, Mahableshwar. at an elevation Oh
4.54O feet in the Western Ghauts, has an average
annual precipitation of PSI inches, while BOMBAY
down at sea-level Though very favoraby exposeoJ'
has only seventy-fve Blanford puts the average
for Cherapunje in the Khasi Hills, at 474 lnches'
which is lower than some older figures while Cal
cutta, bearing much the same relation 10 this
station os Bombay does to Mahabeshwar, gets
but 651-2 The bulk Of this precipitation
comes In the summer, Cherapunje averaging l20
inches for July alone, and In exceptional cases
getting 200 in one month. There is record tor
only twenty-four hours, at this station, OF ao'o
inches, which is only three inches less than the
normal quantity for New-York City for whole
year.
The importance Of getting water into the air
before trying to wiring or shoot 1t out, VIII be
further illustrated if one compares the mean
relative humidity Of certain stations in the United
States with the rainfall. The heaviest known
precipitation in North America outside of the
tropics occurs up on the Alaska coast and OIL
Puget Sound where the warm, steamy air which
overes the Japan Current, or Pacific Gulf Stream,
is swept in against cooler continental atmos-
pheres, or thrust upwards, as In India. AL
Tatoosh Island and Sitka we have an annual
average of over 100 inchesi while OunalasKa,
with mean Of no. had in 1884, the enormous
amount of 1888 inches Official records place the
relative humidity at these places at between 80
and 90 per cent the year around while IN sum-
mer it rises at times above the latter figure.
Mount Washington, with its 100 inches OF rain
and a humidity of sc per cent affords sgnifi-
and 6S per cent Of saturaton. Now, as one
goes northwestward from Texas and Louisiana
coast and its hot, damp climate, toward the great
arid region for which General Dyrenforth's
scheme is mainly designed. not only is there
n steady falling of of precipitation, but also OF
htmospLerc humidity. New-Orleans gets 65
inches of rain annually and has mean humidity
of 20 per cent But Fort Davis, in central West
ern Texas, receives only 20 inches OF rain, and
has only from 40 to SIS per cent of humidity.
Denver gets Is inches of rain, with an average
humidity Of .46. There are places IN
Ncw-Mexico, Arizona, Nevada and Utah with
from only TO IL inches of rain, and they all
have humidity like AZ, 81, 26 and II per cent
Whence can the most skilfpl artisan there pro-
cure raw material wherewith to make rain
Is the air damper aloft than on the earth's
surface? James Glaisher in England and Camille
Flammarion in France made numerous balloon
ascents in order to study this subject. In West
ern Europe on days already rainy or cloudy, they
sometimes. if not generally, found q slight in
crease in the percentage of satuaton with ascent,
I'D to a variable but low level; but on days
already fair, with reasonable dryness at the start,
there was an almost steady, though slow, diminu-
ton in relative humidity with elevation. These
latter surface conditions parallel the situation in
the American ARID tracts more closely than do
the former. apparently; but positive testimony as
TO the moisture of layers of air further up, such
as acronaus might obtain in that part of the coun-
try, is lacking as yet.
How far the agitation OF moist air by heavy
and prolonged bombardment might favor con-
densation is q point on which scientists are not
altogether agreed, perhaps; but however simple
a task this may be, the difficulties are certainly
much increased if the humidity be low. Are they
insurmountabc?