Public ledger. [volume] (Memphis, Tenn.) 1865-1893, 1872-05-30
THE SIGNAL SERVICE.
How storms are F0restalIed and
Property Protected.

signal station in this city has given an
impetus to the investigation Of weather
matters among our citizens. The sig.
nal station in this city is located in the
upper story Of the Irving block, on Sec
ond street, opposite Court Square, On
top Of the building are situated the fol-
lowing weather indicators: The rain
gauge, cylindricalshaped copper ves-
sci, about two and a half inches in
diameter and two feet high, with mover
able, funnelshaped top, which presents
TO the sky receiving surface ten times
as large as the section Of the gauge
proper. If the gauge contains ten
inches of water the true rain fall will be
one inch.
The wind vane is of ordinary con-
struction and indicates the direction of
the wind with accuracy. The anemom-
eter measures the force of the winds.
Four light, metallic hemispherical cups
are fastened upon two rods crossing at
right angles. The rods at their inter.
section rest firmly on an upright spindle,
upon the lower extremity of which there
is an endless screw, which works two
toothed dial-plates. Allowance being
made for the weight of the rods, resist
ance of the air, and friction, it has been
found that five hundred revolutions of
the cups are equivalent to mile of
wind. The two dial plates are placed
one over the other. The scale upon the
outer plate is divided into miles, and
from this the hourly velocity is obtained
The scale upon the inner plate registers
to one thousand miles. The daily veloc-
ity of the wind is obtained from the lat
ter plate.
In the rooms below are the hygrom-
eter and thermometer. placed in such
manner that the direct and indirect rays
of the sun are excluded. The instru-
ments are adjusted TO conform to the
standard at Washington, consequently
it is useless for owners of cheap Their
mometers to sling" them at the gov
eminent instruments, or require the latter
to conform to the sensational figures
appearing on the cheaper and unrelia-
BILE concern. aHIaI
The hygrometer or humidity gauge is
also sheltered. II consists Of two Their
mometers hung upon one frame, with a
wet and dry bulb. The water, conveyed
by capillary action to the thermometer
bulb, is evaporated by contact with the
air, producing an artificial GOODNESS, and
making the temperature of the wet bulb
lower than the reading of the dry bulb.
In warm, clear weather evaporation is
greatest, and the difference between the
dry and wet bulb most considerable.
Before wet weather, and during cloudy
and rainy weather, evaporation is least,
and the readings Of the two bulbs more
nearly conform. When they exactly
coincide, which occurs during dense
fog, and sometimes at the close Of
protracted rain, the relative humidity"
is said to be hundred per cent. The
temperature Of the wet bulb, and the
difference between the two bulbs, being
noted, the humidity of the air is imme-
diately obtained from printed tables ar
ranged for the purpose.
The barometer is the chief reliance of
the meteorologists. The barometer read
ings at stations are calculated for tenn
perature of 800 and additions are made
for elevation above the sea.level. All
improper influences being thus elimi-
mated it becomes possible to define the
great tracts of fair or wet weather, the
areas of high and low barometer men, /
toned in the probabilities.
Five regular observations are taken
daily, each one being practically pho
tograph of the weather, the temperature,
moisture and pressure of air, direction
and force of the wind, fall of rain,
amount of both lower and upper clsud
At this point is also given the stage of
water taken from standard gauges, all Of
which appear in the evening bulle-
tins " and in the river column of the
LEDGER. For full particulars we take
pleasure in referring our readers to the
polite observer at this point, Mr.. Rhode,
who is always ready to show the public
the necessary courtesies.