Idaho County free press. [volume] (Grangeville, Idaho Territory) 1886-current, 1893-09-08

side the cylinder on two curved
surfaces are placed two sheets of
paper each opposite its correspond
ing slide, that are to receive the
record. When sunshine falls upon
one or the other slide a small beam
of light passes through the small
hole and falls in bright spot up
on the paper opposite. This paper
has a peculiar chemical spread
over it's surface and whenever the
sunshine falls upon it the chemi-
cal undergoes change. When the
paper is afterwards washed in
water the parts that were affected
by the sunlight all turn blue. AS
the sun passes across the sky from
hour to hour the little spot of
light passes across the sheet. trac-
ing what will afterwards become
blue line, which will be continuous
if the sun shines steadily, and brok-
en- and interrupted whenever the
sun is obscured by passing clouds.
The slides being moved each day
bring the spots of light to new
places upon the sheets; in this way
a continuous record from month to
month is procured.
The most important condition OF
the air is temperature. Substances
expand slightly with heat. Mercu-
ry expands seven times rs much as
glass. The thermometer takes the
temperature of the air by contact
of particles of air with the bulb.
For temperatures below the freez-
ing point of mercury alcohol Their
mOmeters are used. The alcohol
minimum thermometer carries an
index half an inch long made of
enamel fitted loosely in the bore of
the stem and immersed in the
liquid. When the temperature falls
the index is carried along the bore
and the top stops at the lowest
point reached by the top of the
column of alcohol. The reading of
the top of the index gives the low
est temperature. 1t is reset for
another observation by raising the
bulb end of the thermometer, which
causes the index to slide down the
bore until it stops at the end of the
alcohol column. The minimum
thermometer is set nearly horizon
tai, the bulb end lower than the
top. Earring is apt to displace the
index and cause it to read too low.
For observing the highest temp
erature during the day maximum
thermometer is used. The form in
use at this Station is a mercurial
thermometer with contraction in
the bore of the tube near the bulb,
which appears as if the glass tube
had been squeezed almost together
at that point The passage for the
mercury is so fine at that point
that it will only 60 through with
some difficulty. AS the mercury
becomes warm it is forced to pass
the CONSTRUCTED part of the tube,
flowing through in little spurts.
During cooling the mercury below
the construction withdraws towards
the bulb, but none of the mercury
above the construction can get back
and the top of the column remains
as it was when the bulb was warm
est. In this way the maximum tenn.
perature is registered. 1t is reset
for observation by whirling in the
air by hand or on a pivot. The
centrifugal force developed drive.
the detached thread back to thu
main body of mercury.
These thermometers together
with the wet and dry bulb Their
mometers are placed in thermom
eter shelter consisting of a cubica
house about three feet square will
lattice work on three sides and ,
double roof, raised about five fee
from the ground in an exposed
situation in order to get the accur
ate temperature in the shade.
The mean or average daily tenn
perature is the mean of "a obser
vatiOns made at place every hou
of the day; these are made at onl,
a few places in the world. Tn
approximate mean daily temper
allure is obtained by various shor
processes. The mean of the high
est and lowest temperature of tn
day observed with a maximum an
! minimum thermometer, gives
temperature on the average yer
slightly higher throughout the yea
than the hourly mean at places i
the U. S. This is the mean adopte
by the Weather Bureau at til
r regular meteorological stations.
! Where it is possible to observ
the temperature at a. M, 2 p. n
and 9p. m. a very close approx
: nation to the mean hourly ten
+ perature of the day can be obtaine
: by taking one-fourth of the sum {
t the temperature at 7 a. M, 2 pm
: and twice the 9 p. m. One-half tn
: 8 O'Clock morning and evening
f gives the temperature in the U.
: only few tenths Of a degree belo'
}. the mean of the day.