Burlington weekly free press. [volume] (Burlington, Vt.) 1866-1928, 1878-07-19
VIII Il Rain s---Facts About the Weather Reports
HOW "PRoBABIL1TIEs" ARE AscERTAINED.
From Talks by the Professor" In Christian Union.

the labor and expense necessary to carry
on? You often see in the papers littl
paragraph of n few lines telling the ''pr6
liabilities" Perhaps you think that som
mysterious person climbs up on top of HI
house, looks around a little at the cloud
and the weathercock on the barn, and the
goes down and says that he's sure there
going TO be II spell of weather of some kind
What do you say TO finding out all about it?
There are connected with this service
about two hundred stations, scattered all owe
the country.
These stations are established and equip
ped on purpose for observations and are no
connected with any other branch OF the gov
ernment seryice-such as naval stations AM
the like
The central office is at Washington. A
all stations there are three observation
taken viz, 7:35 a. m, 80 p. M, and
O'Clock p. III. washington time), the result
of which are telegraphed to Washington
There are also three or four observation
taken daily q a. m, D. M. and 9p. NJ. } ant
sent by mail to headquarters once week
But the telegraphic reports are those in which
We are most interested, for upon their arriva
at Washington chart is Immediately made
out and sent all over the country. So yor
see that there must be three Of these charts
made and sent ont every day. The reports
telegraphed include the state of the barome
ter, Thermometer. hygrometer Showing the
| moisture Of the atmosphere), direction of the
wind, velocity in miles and pounds of pres
sure, kind and amount of upper and lower
| clouds, with the direction and velocity Of
each stratum, rain, hail snow or sleet as the
case may be the report closing with state
ment of the general character OF the weather
| These reports are sent in cypher not on ac-
| count of secrecy, but that they may be more
accurate. especially where figures are neces-
sary.
If the wind is from the southwest and the
weather ioggy they use the word Hermit. "
Should the temperature stand at fifty degrees
the word Fight is the one sent. You can
readily see that this system saves much time
| as well.
On an elevated place, where the wind is
unobstructed, are four hollow hemispherical
cups placed in a horizontal position so as to
| catch the wind. These are at the top of a
registering rod. This rod is in connection
with a disc that is in its turn connected by
| electricity with a registering drum in the
| Office of the station. This little machine is
called an draHCmeter. The disc on the rod
with the cups is so arranged that it makes
| one revolution as each mile of wind passes,
and little wire point on the disc comes in
contact with another point upon stationary
| edge at each revolution. As these points
come together the electric circuit leading to
the registering machine i'll the office is COM
| plete, and SO for Il second q small magnet in
| the machine is released, giving little jerky
motion to pencil point that is resting on
| drum covered with paper and kept revolving
| by means of clock work. The paper over
this drum is divided by lines into spaces rep
| resenting hours and fractions thereof. Tie
pencil follows n straight line until the mag
net is released. when the lead makes little
mark TO the left and then flies back again.
Now as you know that the pencil moves
every time a mile Of wind has blown past,
you can see that the spaces between those
little marks on the drum of the dlieHOneter
represents miles, and by seeing how many
time-spaces las lined on the paper) have been
passed by these marks since the hour began,
you can tell how many miles per hour the
wind is blowing.
You who live in seaport towns have often
noticed the harbor full of vessels at anchor
late in the afternoon. You wonder perhaps
why they don't sail away, for the sky is
clear and the wind moderate. But if you
knew as much as do the captains OF these
vessels you would look up at that high
building yonder. where u red flag with n
black center is flying. That is the caution
AIRY signal for Washington has telegraphed
that storm and wind are coming. At night
this signal takes the shape of a red light
from u lantern on the Gag staff.
In New York city the signal service Office
is situated on the top OF the Equitable In
surance building. which is in the lower part
of the city and near the bay. The princi-
prl telegraphic signal stations send 10 the
New York office three times daily. The
clerk here furnishes all the different ex-
changes and maritime offices with transla-
tions of the cypher. There is also Far
mer's Bulletin' made out at all the principal
signal stations. Most OF the stations through
out the country have the necessary type and
presses, and the probabilities are printed
early in the morning (three or four o'clock
and mailed to posimasters in the vicinity.
These bulletins are hung up in the postoffices
and the farmers can examine them when they
come for their letters Il is often Of great
importance for the farmers to know when it
is going to rain. The New York station sends
out 70i of these bulletins every morning.
As reports are received at the Washington
office the clerk takes a chart and draws red
lines upon 1t connecting places having the
same atmospheric depression. Thus the
map shows in curving red lines the locality
wherein the pressure is at its highest and
lowest points. High pressure always moves
toward low pressure. BY low pressure the
Professor simply means less air. as shown
by the barometer. You've often heard iof
storm centers. A storm center is at the
locality where the pressure is at the lowest
point, and you know that mature abhors
a vacuum" the denser air surrounding this
storm center must rush in TO fill the space.
The greater the difference between the at
mospheric pressure at the storm center and
that III its vicinity. the greater the force and
speed of the wind, of course and as air has
been taken from the neiGhborhood to make
up the deficiency, 20 that in turn has TO be
supplied from its vicinity, and so on back
over the country. the wind getting weaker
and weaker as it leaves the storm center.
Now, as all the signal stations have been
informed by telegraph of this storm center,
the officers can ioretell the approach of the
wind very readily, and by knowing the
amount of moisture the temperature and
the amount OF cloudiness ut the different
localities, the state of the weather accom-
panying this wind can easily be determined
There are quite often several storm cen
tiers at the same time iii different parts of
the country which lead the winds lively
race, each storm center causes the wind
to blow in two different directions. For in-
stance Let us suppose there is storm
center III Tennessee, and that the highest
atmospheric pressure is in Eastern Canada,
most of the country east Of Tennessee would
have Il northeast wind, but west of the
storm center the air would rush IN from the
opposite side, and the direction OF the wind
would be reversed.
The station officers call high wind II
storm, whether accompanied by rain or not.
Sea captains seldom venture out of harbor
when the wind is blowing at the rate of
twenty five miles ali hour. When the wind
is blowing from forty TO sixty an hour it is
called gale From eighty 10 one hundred
and fifty miles II hurricane. You have sell
dom felt the wind at greater speed than
sixty miles an hour
The weak point IN the civil service is some
thing the service cannot help at present.
They have no means OF recording the state
OF the weather ON the Atlantic and so
when the WIND Is from the east II ls pretty
hard telling what IL going to happen. The