The Cairo bulletin. (Cairo, Ill.) 1???-1928, 1905-09-18
HOW WEATHER is
MADE IN CAIRO
Concluded from Fourth Page.)

tConeluded from Fourth Page)
tween the bulbs ard the protecting
sheath is perfectly exhausted of air.
During the Time that the sun is shining
this instrument with its electrical al
tacbment makes a record every minute
OF that fact The instrument in use
for collecting and recording the rain.
fall at Cairo is what is known as a
tipping bucket rain gauge. The So
called bucket is double compart.
ment affair. 1t is. SO arranged that one
OF the compartments is presented in
such a way that it will receive and
retain the water delivered through The
funnel of the collector. The weight
OF the bucket ana the position of its
center OF gravity have been so adjusted
In relation 10 its supports that when
one of the compartments has collect
ed quantity of water equivalent to
one one-hundrolths OF an inch of rain,
me bucket tips and empties and at the
same time presents the other compart
ment 10 collect the incoming water.
Each tip of the bucket records cleo
Ltrically in the forecaster's office. The
basis on which the amount of rain is
measured is the depth of water that
would accumulate on a level surface
If all of it remained az 1t fell and none
flowed or soaked away or was lost by
evaporation.
The thermometer consists Of cups
and arms aud spindle and dial mechan-
ism The cups are as nearly hem
spherical as possible ard are made
OF aluminium. The dial wheel of the
thermometer is graduated into 100
spaces, near the periphery are set ten
small 'contaet pins" eaudistant. AS
the dial revolves the contact pins are
brought consecutiyely against a deli
cate spring; this in turn is forced
outward and the point touches plat.
mum tipped contact post, an electric
circuit is completed ana mile Of
wind is recordeh The steel arms arc
| SO constructed that 500 revolutions
of the cups are required to cause the
dial to move forward one-tenth Of it's
| circumference. or in other words a
mile of wind in passing over Cairo
causes the sups to revolye 800 times
! The anemoscope or wind vane, is me-
chemically ana electrically arranged &c
that the direction of the wind is re-
corded continuously in the forecaster's
office. In the office are located the
barometer and self recording instru-s
ments. One of these, a self-recording
barometer, or Paragraph as it is
known, records continuously the
weight or pressure of the air. Every
lfuctuation, no matter how slight, is
shown by this instrument
/ The meteorograph. or triple regis
| ter, IL an interesting instrument to
watch, particularly during stormy
weather. 1t performs It's work in a
human-like manner in automatically
| recording the sunshine, rainfall wind
velocity and wind direction.
! BY no means the least interesting
| feature of the work done at the To-
cal office Of the weather bureau is
the preparation and issuing of the
weather maps and bulletins. They
are received daily by telegraph at
the forecasters office, reports from
50 regular weather bureau stations
and ten special rain stations. In adj
dition to these there are received spec
| ial reports from certain rainfall and
river stations where unusual conditi-
ona obta n. The Cairo river district
composas the lower Tennessee, lower
Cumberland the Ohio from below
Louisville to the mouth, the Wabash
| from headwatcrs to the mouth and
the Mississippi from below st. Louis
to Cairo. The territory is looked az
ter by the local office and all warn
\ ings of freshets and floods to this ter
ritory are prepared at, and issued
| from the Cairo office.
| There are issued daily from the 10.
cal off ce about $50 weather maps.
and about 200 postal cards containing
the weather forecasts During the
winter ana spring the issue is mich
larger, The work Of preparing these
reports has to be done hurriedly and
accurately in order that the informa-
ton may be distributed promptly and
reliable. The telcgraphc messages
commence coming in by $3.50 a. m,
and usually by 1880 a. NJ. the weather
maps are in the mail for points in
western Kentucky, western Tennessee
IS0nthefn Illinois and southeast Mis-
souri, During the last two or fhree
\ years the maps have been furnished
| regularly to a. number Of schools in
'EScuthern Illinois. The, teachers make
luse of the. maps In connection with
their work in physical geography Al
many of the schools the pupils show
a very lively interest in the map,
study il carefully and in course of
time become familiar with the meth
DDS used in forecasting the weather
a tonic that makes sick people well
Drives out all impurities thar collect