The Florida agriculturist. [volume] (DeLand, Fla.) 1878-1911, 1878-07-24
HOW THE WEATHER IS
F0RET0AD.

In former times, the chief herald
of the weather was the almanac.
which ambitiously prophesied whole
year of cold and heat, wet and dry,
dividing up the kinds of weather
qnite impartialIy, if not always cor
rectlv.
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 exact information to
the country; and they have been
thrown quite into the shade Of late,
by one who is popularity known un-
der the somewhat disresDeotfuI title
OF "Old Prob, or cold Probabili-
ties. " He has become the Herald
of the Weather to the sailor, near
the rocky, dangerous coasts; TO the
farmer, Watching his crops, and wait
ing for good weather to store them ;
90 the traveller, anxious to pursue his
journey under fair skies; and to the
boys and girls who want to know be-
fore they start to the woods for a
picnic, what are the "probabilitios "
as to ram.
Every one who reads the daily pa
per is familiar with the " Weather
Record, ISSUED from the "War De
partmcnt, office of the Chief Signal
Officer, " at Washington. These re-
ports give, first, q general statement
Of what the weather has been, for the
past twenty-four hours, all over the
country, from Maine to California,
and from the Lakes TO the South At
lantic States, and then the "Proba-
bilities," or "Indications, for the
next twenty-four hours, over the same
broad territory. The annual reports
Of the Chief Signal Officer show that
in only comparatively few instances
do these daily predictions fail Of full
6llment.
The reason these pyophesies are so
true is simple and yet a wonderful
one. The weather itself tells the OBJ
server what it is going to do, some
time in advance, and the telegraph
sends the news ali over the country,
from the central signal Office at
Washington.
We shall see, presently, how the
weather interprets itself to cold
Probabilities. Although it has
proved such a fruitful subject Of dis
0ourse in all ages, yet | am afraid
many people who pass remarks upon
it do not really think what the wealth
er is made of. Let us examine its
different elements.
The atmosphere has weight, just as
water or any other fluid, although it
seems to be perfectly bodiless. We
must comprehend that, the transpa-
rent 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 On instrument called
barometer. Generally speaking, the
falling Of the mercury in the tube of
the barometer indicates q rain, and
ITS rise heralds clear weather. Some
times the rise is followed by winds,
frost and ice. " hat these changes
really Indicate, however, can only be
determined 10y comparing the baro-
metic changes, at certain hours In
number OF places very far apart. This
Is done by the Signal Service. Obser-
vations are made at one hundred and
forty stations, in different PARTS of the
country, At given hours, and the re-
suits photographed at once to Wash
jngton, where our faithful weather
ssIcrk receives them, reasoning out
of them the probabilities " which
be publihes three times III every
twenty.tour hours.
But the atmosphere varies not only
i'm weight. but also in temperature.
The thermometer tells us of such
changes.
Besides this the air contains a great
amount Of moisture, and it shows as
much variation in this characteristic
rs in the others. Fer the purpose OF
making known the changes in the
moisture OF the atmosphere, an instru-
naent has been made called "wet-
Bulb" thermometer.
We are thus enabled to ascertain
che weight or pressure, the tempera-
lure, and the wetness Of the air, and
NOW it only remains for us to meas
Gre the force, and point out the di-
rection, OF the wind. This is done by
che familiar weather-vane and the
thermometer. The vane shows the
nlrpcfinm and the anemomnier l. an