The Princeton union. [volume] (Princeton, Minn.) 1876-1976, 1878-08-14
How the Weather is Foretold .

t& d r u
How the Weather Is FOretOld.
In former times, the chief herald Of
the weather was the almanac, which
ambitiously prophesied a whole year Of
cold and heat, wet and dry, dividing up
the kinds Of weather quite impartially,
if not always correctly.
But the almanac, good as it was now
and then, and the weather~wise farmers,
correct as sometimes they might have
been, were not always able to impart ex-
act information to the country; and they
have been thrown quite into the shade of
late, by one who is popular known under
the somewhat disrespectful title of "Old
Prob,:' or sold Probabilities" He has
become the Herald of the Weather to the
sailor, near the rocky, dangerous coasts;
to the farmer, watching his crops, and
waiting for good days to store them; to
the traveller, anxious to pursue mis- Jour
ney under fair skies; and to the
girls and boys who want to know,
before they start to the woods for a pic
mic, what are the probabilities as to
| rain. .t t~
Everyone who reads the daily paper is
familiar with the "Weather Record" is
sued from the "War Department, office
of the Chief Signal Officer at Washing
ton. These reports give, first, general
statement of what the weather has been,
for the past twenty. four hours, all over
the country, from Maine to California,
on frsnyo %h1 Ta11 ko AN
States; and then probabilities" or In
| dications, for the next twenty -four hours,
over this same broad territory. The an.
nual reports to the Chief Signal Officer
show that in only comparatively few in
stance do these daily predictions fail Of
fultillment. sIl- ..,,. ~...... ...s
The reason these prophecies are so
true is a simple and yet wonderful one.
| The weather itself tells the observer
what it is going to do, sometime in ad.
vance, and the telegraph sends the news
all over the country, from the central sig
nal office at Washington.
We shall see, presently, how the wealth
er interprets itself to :'Old Probabilities"
Although it has proved such fruitful
subject Of discourse in all ages. yet am
afraid many people who pass remarks
upon it, do not really think what the
weather is made of. Let us examine its
different elements. # L,.ar- 4.5
The atmosphere has weight, Just as wa
ter or any other fluid, although it seems
to be perfectly bodiless. We must COM
prehend that the transparent invisible air
is pressing inward toward the center of
the earth. This pressure varies according
to the state of the weather, and the
changes are indicated by an instrument
called barometer. Generally speaking,
the falling of the mercury in the tube of
the barometer indicates rain, and its rise
heralds clear weather. Sometimes the
rise is followed by cold winds, frosts and
ice. What these changes really indicate,
however, can be determined only by com
pairing the barometric changes, on certain
hours: in a number of places very far
apart. This is done by the Signal Ser
vice. Observations are made at about
one hundred and forty stations, in differ
ent portions of the country, at given
hours, and the results are telegraphed at
once to Washington, where our faithful
weather clerk" receives them, reasoning
out from them the ssproDabilities'' which
he publishes three times in every
twenty-four hours. But the atmosphere
varies not only IN weight, but also in
temperature. The thermometer tells us
of such changes. ~
Beside this, the air contains a great
amount of moisture, and it shows as much
variation in this characteristic as in the
others. For the pnupose Of making
nV1Jy1f ho 0hon 49, HxlI-
atmosphere, an instrument has been in
vented called wet bulb" thermometer.
We are thus enabled to ascertain the
weight or pressure, the temperature, and
the wetness of the air, and now it only
remains for us to measure the force, and
point out the direction of the wind. This
IS done by the familiar weather-vane and
the thermometer. The vane shows the
direction, and the thermometer is an in
strument which indicates the velocity of
the wind
tits by a right understanding of all
these instruments that the Signal Service
officer is enabled to tell what the weather
says of itself; for they are the pens with
which the weather writes out the facts
from which the officer makes up his re-
prorts for the benefit of all concerned.
Thus, however wildly and blindly the
storm may seem to come, it sends mes
sengers telling just where it arose, what
course it will take, and how far it will ex-
tend. But it tells its secrets to those on
~ who pay strict attention. III anes II.
Flint, IN st. Nicholas for July.
s@ Two Humble Heroes.
b z . . Il \ b. e. 81 . 3