The Democratic advocate. [volume] (Westminster, Md.) 1865-1972, 1881-09-03
Our Olio.
How Indications" are Made.


Robert Boyle, speaking of his own obser.
vations with the barometer u hope il
will help US Que step towards the rearing a
theoretical pillar or pyramid, from the top
OF which, when raised and assembled, we
may be able TO see the mutations Of the
weather at some distance before they APP
Proach Us; aud thereby, being able to pre-
diet and iorewarn, many dangers may be
prevented aud the good OF mankind very
much promoted The pillar or pyra-
mid which foated in Hooke's mental eye
has beeu steadily rising, though the mate
rials Of which it is built are not itheoreli
cal, but very matter -oi.iact observations
OF the barometer, thermometer, auemome-
ter (wiud measure, , aud other Instruments
Ii IS needless to say that the old English
philosophers hope has been realized on the
broadest scale in the United States by the
Army Sigual Service, but many people are
as uniformed of its methods of collecting
/ weather reports and forecasting weather as
I llooke was. As contribution to public
/ information on the methods of collecting
and transmitting the reports by telegraph,
q short paper Of much interest, prepared
by Lieutenant Caziarc, Acting Signal
/ Officer, and issued BY direction of General
Hazen. Chief Signal Officer, has been pub
/ lished.
The first thing done each day by the
Central Office at Washington, before it can
formulate the weather predictions, popu-
larly known as Indications, is to obtain
from all parts of the country accurate and
/ simultaneous observations Of the state of
the barometer, Thermometer, wind diree-
tions, and velocities and the cloud coudi-
tons To be Of use in calculating coming
weather changes these observations must
be taken at all the stations at the same
hour aud minute aud be telegraphed to the
Central Office very promptly. When from
its ninety stations stretching from Maine
to Texas, aud from the Pacific Coast to
the Atlantic, aud connected by cable with
the West Indies, the chief signal officer
receives his telegraphic weather reports,
the scientific materials for the "Indica-
tions are in hand. But these telegrsphie
reports are all in cipher, and must be
translated Then they must be all entered
10 figures aud BY symbols on n large map
Of The United States, each stations obser-
yations reuciled aud symbolled at the OBJ
servers point on the map. The prelimi-
nary work is BOW done, but before it can
be utilized fer indications the lines Of
equal barometric pressure must be drawn
on the map, connecting those stations
where the barometer reads the same; SINH
larly lines Of equal tcmperature-isOther
mals-SonReetiBg stations reporting the
sane temperature. By these lines the
waves Of high aud low barometer, hot
waves and cool waves, are defined, aud the
meteorological gains tolerably clear idea
Of the currents and er0ss-currenls in the at
mospberic ocean ovespreading the eoun-
try, aud clear view OF any s,oFm-centre
crossing IL, aud the Wind-iorces or rain /
belts that are driving or attracting it 10 |
various directions The cyclones aud an-
ii-eyelones defined on bis map are also out /
lined by the cloud areas or clear weather l
areas. This method Of grouping aud graph |
ieally dellneatiag the phenomena and loeat- /
ing conflicting aerial masses on a map of 4
the storm field enables the meteorologist to |
catch 4 bird s-eye view Of the weather ia /
every part of the eountry al the same hour |
He can now study the probabilities But,
il must be remembered, the disposition of !
the elemental forces, as thus mapped, is
eeaselessly changing, so that in forcasting
the meteorological results, TO occur within /
oue or two days from the tine his map was |
prepared, the meteorological must apply the 1
many laws Of storms that control the wealth !
er changes No two weather maps pre- I
sen, the sane combinations Of barometric |
aud other weather factors, and hence in |
deducing the Indications from them,
from day to day, there is DO room for en-
pirieism.
This Is, Of course, but an outline Of the
work requisite for a single forecast, or for
preparing the weather "bulletin,' which |
sums up the prevailing atmospheric con-
ditions in the different sections of the 1
country at the hour Of its issue from the 4
Ceatral Office at Washington. Three
times each day in the year it IS repeated at 4
the Central Office, and deductions made 1
from the three daily wealher-maps thus pre-
pared The barometer is the master key to
the provision Of the atmospheric pheuom-
ena. The greater the inequality Of the
all -presSures which it records, the greater
will be the wind force between the regions
of 'high" and low pressure. The d.
reetion of the regions Of high and low
pressure relative to the wind is determin-
cd in the northern hemisphere by the law,
Stand with your back to the wind, and
the barometer will be lower on your left
hand than on your right The reverse
OF this holds good for all places south of
the equator. IL is by this lay (miscalled
Buys Ballots Law that the mariner threat
eued at sea by an invisible, but not distant,
hurricane, may gain pretty clear notion
Of where the dangerous storm is raging,
and thus feel reasonably sure Of the way
to escape it, But the thermometric iGdi-
cations on the weather map are of most
material value, half dozen readings
sometimes uuerringly revealing the APP
preach of big ''eold wave, amply large
enough to cover half the country, and
control its weather for two or three days.
The "relative humidity" Cor comparative
reports reveal the districts over
which rain Is preparing or likely to fall 1
from the lower strata of the air, though as
vet weather science has devised no instru-
nent to unmask the hygrometric condition
Of the upper atmosphere. These are
family indicated, however, by the cloud |
forms which are daily reported aud enter
"a on the Signal Service weather maps
To revert to Lieutenant Caziarc's paper
detailing the work of collecting the mete-
orological data, the Central Signal Office
at Washington has Geographic terminal
circuits running directly to New York,
Knoxville, and Lake City,
Florida and the Atlantic Seacoast Tele-
graph connecting with the West Indian
stations. At 7.25 a m, and 1926 p. m.
and l1.25 p. m, Washington mean time,
each day, the station ttrthest from the
central office on each circuit running d.
rectly into that Office starts his report, it
is copied by every station on the circuit;
as soon as this station is through the next
station sends; he is followed by the next,
and so on until every station has sent its
report" While this is being done all
othar circnitS are nollactinp renorts M the