Rock Island Argus. (Rock Island, Ill.) 1893-1920, 1905-04-26
MEASURING RAIN
Observer Sherier Tells How
Depth of Fall is Automat-
icaIIy Reg stored.
THEORY OF THE CYCLONE
Weather Men Hope Ultimately to Be
Able to Make Predictions
Long in Advance.

Visitors at the weather bureau Office
during the steady downpOur of rain
are sometimes startled by a peculiar
sound, not unlike that made when a
musket is cooked. This sharp click.
repeated every few minutes, the inter
val depending upon the rate of rainfall,
is made by the recording pen of the
rain gage register Every movement
of the pen indicates that one-hundredth
of an inch of rain has been collected
in the gage upon the roof
The rain gage itself consists of a
sort of funnel exactly u inches in dia-
meter, set over a cylindrical reservoir.
The water falling within the collector
or funnel is conducted into a tipping
bucket that has two equal compart-
ments. This double bucket rests upon
a pivot in a frame, and, while rain is
falling, rocks in such a manner that a
compartment is always directly be
meath the small opening of the funnel.
After one-hundredth of an inch of wat
er has fallen into the bucket, it tips
emptying the rain into the reservoir
and the other compartment. or bucket
is brought under the funnel to be fill
ed. AS the bucket tips. it closes an
electrical circuit, causing the pen on
the register downstairs in the Office
to make a short mark upon a record
sheet that is divided into spaces repre-
senting time and is moved at a uni.
form rate by clock work. so that il is
possible TO tell exactly what amount
Of water has fallen within any given
interval. AS a check upon the work
done ~ the registering apparatus. the
water collected within the reservoir
of the gage is drawn off into cylin-
drical tube and measured with a stick
graduated to inches and tenths. The
area of the opening in the tube is just
one-tenth the area of the mouth of the
funnel. or collector, and The depth of
water in the tube is thus just ten times
the depth on the level One-tenth of
an inca on the graduated stick is
therefore equal TO One-hundredth of an
inch of actual rainfall. This multiply
ing arrangement is used in order that
the measurement of small amounts of
rain may be made with accuracy.
barometer Falls.
A@tcNiilS lllC rainfall register ana
giancing at the record made by the
self registering barometer. we notice
that the line traced on the sheet shows
a steady fall that began some hours
before the rain commenced and is
pitching downward more sharply as
the wind increases in velocity and
veers towards the south. The storm
may ne of the type sometimes called
''nOrtheaster.' but. while the wind was
from the northeast before the rain
commenced and for considerable
time after it began. the morning map
probably showed the storm center TO
be over Nebraska, moving towards the
northeast. This rapid fall in the bar
ometer. together with the increasing
wind velocity, and the shifting direc-
ton, indicates that the bottom of the
great whirl in the atmosphere. or cen
ter of the storm, is not far to the west.
ward of the observation station.
In former article on cold waves. it
was explained that the lows" or cy-
clones, or storm centers, shown on
weather maps are vast eddies in the
atmosphere that, besides having a ro-
tary motion. move towards the east at
an average rate of about so miles per
hour. The circulation of the all
around these immense whirIs is spir.
| ally upward and inward TO the center,
in direction the opposite TO that TAX
en- by the hands of a watch. Along the
| eastern and southern sides of the
storm, high temperatures and cloudy
| skies are observed. with more or less
| rain. while clear, cold weather prevails
to the westward and northwestward
| When one of these disturbances is cen
| trail over Oklahoma or Kansas. the
rain area sometimes extends eastward
TO the Atlantic coast and northeast
ward To New England. The point OF
| greatest rainfall in well developed
areas of low pressure is generally
considerably to the southeastward OF
| the center
Follows Path of Center.
Knowing that as a rule. rains occur
along the eastern side of the cyclone
the forecaster is. in most cases, chiefly
| concerned in determining the future
path OF the storm center and the rate
at which IL will move towards the At
lantic. At all places in and near its
path, there is likely to be increasing
| cloudiaess. followed by rain, as the
storm center approaches; and these
conditions, will, in turn. be succeeded
| by clearing and cooler weather as the
cyclone passes and the atmospheric
conditions along its western side are
! encountered.
Mountain ranges exert a powerful
/ influence upon the rainfall of a local
| ity. In fact, the scanty rainfall of the
| semi-srid portions of our country is
due to the location of those regions
with reference 10 mountain chains. An
ideal condition of abundant rainfall
exists when warm. moist bodies of air
encounter mountains and are forced