Chicago eagle. [volume] (Chicago, Ill.) 1889-19??, 1893-03-18
WORK OF FORECASTING.
How it Is Done In the United States
Weather Office.

The work of forccasting is, | under
stand from foreigners who have visited
our Washington weather bureau, more
thoroughly and completely done here
than in any other country. In the first
place, American ingenuity has brought
the principle of simultaneity, If | may
use the term, in every detail of the work
TO the greatest perfection; but what is
far more Important in the matter of fore
casts, no other country presents so vast
territory from ocean to ocean at which
simultaneous observations can be taken
at SO many stations all under the control
of one chief officer.
OF course, numerous complaints have
been heard throughout the country OF
the unreiability of the weather fore
casts, and yet careful record shows
that during the past ten months the
weather has been accurately forecaste0
on an average of eighty eight times out Of
100. Naturally, however, the twelve
times when the weather has varied from
the forecasts they have attracted great
deal more attention than the eighty
eight times when the forecast has been
fulfilled to the letter.
| In the annual report of the Secretary
of Agriculture for 1891, the record of the
weather at principal points Throughout.
the United States is given for every day
in the year, by means of diagram
Such record for a series of years will,
taken in conjunction with the condition
OF the various important crops, and of
the plant diseases or insect pests by
which they have been affected, undoubt-
edly form a most interesting study, as
they indicate more and more surely to
agriculturists the correlation between
meteorological conditions and the sew
eral vicissitudes by which our various
agricultural products are affected.
In closing this brief sketch of one of
the most interesting features of the me-
neurological works in the United States, it
may be interesting to describe briefly one
or two of the methods adopted for keep
ing an accurate record of meteorological
conditions One of these is the record
| ing of sunshine automatically. An in
! strument has been devised which follows
the course of the sun in such manner
as to reflect its rays upon chemically
! prepared surface which gradually changes
color whenever the sunshine strikes.
Naturally, if the sun be completely over
cast there is no change of color, while,
If partially cloudy, the surface is blurred
or the color changes titfully, according
as the sun shines or is obscured. The
course of the sun from sunrise to siin-
down and the periods when the sun
shines or is cloudy are thus accurately
represented upon the surface of the ma
chine.
Another ingenious device records auto
matically the force of the rainfall at diff
ferent periods of the day, in addition to
giving the total precipitation. The
principle by which this is accomplished
is very simple, the rain gauge containing
pan which tips over whenever it is full,
depositing the contents in the rain
gauge proper The fitting of the pan is
automatically recorded, and the quantity
of what it contains being known, and
the length of time taken for it to fill be-
ing shown, the rate of precipitation at
any time Of the day or night can be cal
culated very closely.
Tho total cost of running the weather
service Of the United States is little
under 5000, 900.