Fayette County herald. [volume] (Washington [Washington Court House], Fayette County, O. [Ohio]) 1860-1???, 1874-05-14

Buffalo.
Knowing that the FAYETTE COUNTY
HERALD finds its way into the house
hold of many, if not all the intelligent
families of Fayette county, and many
other counties throughout the State as
well as many other States, thought
description of the instruments used in
an Office of observation of the wealth
er, from which predictions of what
the weather will probably be for the
next twenty-four hours, styled "prob
abilities" are made, would be interest
ing to at least the intelligent class of
readers of the herald.
The instruments may be enumera
ted as a Standard Mercurial Barome
ter, one Hygrometer, three Thermome-
ters, one Anemoscope or wind-vane,
one Anemometer and one Pluviameter
or ain-gauge.
An observation consists of reading,
with great precision, each of these in
struments, with the addition of read
ing the condition of the sky, with
the naked eye) stating the amount of
clouds, if any, and of what class and
the direction they are moving from.
The barometer, which consists of a
cylindrical glass tube, hermetrically
sealed at one end, which is filed with
mercury and rests upon the mouth of
cistern filed with mercury and both
placed in a guttap ercha case, with a
screw at the bottom of the cistern to
raise or lower the mercury to an ad-
justment-a little ivory point-at each
J observation, and scale and Venier to
adjust to the top of the column of
mercury in the tube, and is then read
inches, tenths, hundredths and thou
sandths of inches To this frame is
attached a thermometer, technically
called, an attached thermometer. At
each observation Of the barometer,
the attached thermometer is read, the
mercury adjusted to the ivory point in
the cistern, and the venier adjusted
just to the top of the mercury and then
read. The observed height of the mel
curry, as just read, is corrected by the
attached thermometer for temperature.
Heat expanding the column, hence a
change Of temperature may affect the
height of the column of mercury
without necessarily showing a change
of pressure, and for this reason the
thermometer is corrected for tempera-
ture. 1t is then corrected for elevation
above the level of the sea by the ex-
posed acknowledgements for ell
ovation varying with the temperature
of the atmosphere. Each baromer is
compared with standard barometer
at the Chief Office in Washington, land
the difference in readiug of the two
accompanies each barometer when
sent to any station, and at each obser-
yation the barometer is corrected fol
temperature, elevation above the level
of the sea and instrumental error
The two last corrections are more
essential in these reports than would
be to an individual who keeps a boron
ter simply for his own informotion
for the reason of having these reports
compared with those from other sta
tions.
Upon the roof of the building il
which is located the Signal Office, i;
built small building of lattice work
constructed for the protection of tht
thermometer and hygrometer from th
weather yet, it is so constructed as tc
allow the air to freely circulate thro1gl
/ it and get the true temperature of tn
air. In this building across the cente
0 are suspended, away from the WOO
some little distance, the thermometer
and hygrometer, being freely exposed
facing the north, and at the same tim
protected from any radiating objec
and for these reasons must be proper
ly exposed to get the true temperatur
of the air. In this building (techni
cally called an observatory are thre
thermometers and 'swet- bulb hygrc
meter, which is simply two thermom'
ters, side by side, about three and
half inches apart, and at the bottol
of one is attached a round wick, CO.
ering the bulb, which is saturated wit
water and this wick is connected wit
a small cup containing water, whic
keeps the wick continually saturated
and habitually causes this thermom
IT. ter read lower than the dry thermom
ter next to it, and the difference in I'll
, readings directly measures the evapC
> rating power of the atmosphere, an
indirectly the per cent. of humidity
the air Owing to the difference in I'll
readings of these two thermometer
wet and dry bulbs, the per cent.
S, humidity the air contains has be,
calculated, and tables prepared whi
state the amount
The exposed thermometer in th
observatory is simply a standard me
y curial thermometer, and is suspend
in like manner as the hygromet
ou thermometers.
;. A short distance beyond the e
. posed thermometer are the self-reg
20 tering maximum and minimum thu
81 mometers, the former containing mt
curry, and the latter alcohol. The ma
imum thermometer is constructed
having a little above the bulb slie
q contraction in the bore of the tn
and the thermometer being placed
the incline, as the heat expands t
mercury in the bulb its density is
minished and it is forced up throu
old the contraction, and as it gets COLI
it's density is increased and prevel
it from returning through the contr
ton to the bulb, and remains at
e highest degree, until forced back
- the centrifugal motion, when s
which is done at the last observati
of each day-1O :52 p. m.
The minimum thermometer conta
alcohol, and is also placed on the
cline, and within The tube is INNER
q very small glass rod or index, SIN
er than the bore of the tube, which
brought in contact with the extrem
of the column, and on account of
capillary adhesion between the alco
and the glass, when the alcohol c
tracts it drags along with it the 81
index but when the alcohol expa