St. Charles Republican intelligencer. (St. Charles [Charles City], Iowa) 1856-1857, 1857-02-05

! thermometer is as follows: A glass
tube with a very small bore and hav-
ing a spherical or cylindrical reservoir
at erfc end, is filed with mercury
The mercury is then boiled in the tube
in order t. free It of all air that it may
contain. When this is done the tube
is closed and allowed TO cool. 1t is
then attached permanently to q thin
metallic plate, after which 1t is placed
in mixture of melting ice and water
and the point at which the mcrcurial
column in the tube stops, is marked on
the metal plate. This is the freeing
paint of all thermometers. The instru-
mcnt is then plunged into boiling wa
ter and the point where the column
stops is marked. This is the boiling
paint of all thermometers. The space
ibctwccn the points marked is divided
into $50 equal parts, ard spaces equal
to these are marked off below the
freezing point, and above the boiling
point, as far as may be desired. These
spaces are called degrees and as the
termination of the mcrcnrial column,
by the abstraction or addition of heat,
passes over certain number of these
spaces, the thermometer is said to rise
or fall so many degrees.
AS a matter of convenience these
degrees arc numbered on the metallic
scale, commencing at some prominent
point. This point of beginning might
be any where, and the numbering pro-
coed either upward or downward, but
on our common thermometers the be-
ginning or zero is placed 80 spaces be-
low the freezing point, and the num-
boring proceeds both upward and
downward from this ocro. The de-
grces below this point are megakiv,
those above this point are poaitirc-
For instance, if the mercury stands Is
spaces above this zero, we should say
that it stands at Is degrees, but if it
be ID spaces below this zero, we should
say that it stands at MINIS Is degrees,
or IL degrees below zero
OTHER THERMOMETERS.
Such is the construction of the COM
mon or Fahrcnhcit's thermometer. 1t
is used mostly in the United States
and England In France and Gcrma-
ny the thermometer most in use is
that of Celsius, or the ccntigradc. In
Russia, Rcaumur's thermometer il
used. They arc both constructed pre-.
cisely like Fahrcnhcit's except in the
graduation of the scale. In the cent?
grade the space between the freezing
and boiling points is divided into 100
equal parts--in Rcaumur's this space
is divided into so equal parts the
spaces in both cases being continued
in both directions beyond the fixed
points as far as may be desired. The
zero in both is placed at the freezing
paint, differing in this from Fahrcn-
hcit's,) and the numbering takes place
in both directions. The boiling Paint
on Fahrcnhcit's thermometer is at 2l2
degrees, on the ccntigradc at 100 de-
grces on Rcamnur's at so degrees.
The freezing paint on Fahrenheit's is at
81 degrees, on the ccntiyradc at zero,
on Rcaumur's at zero Thus we have
three different methods in prominent
use of expressing the same thing all
cqualt.r. definite, simply differing in
FORM
a DEGREE OF HEAT.
We see from this comparison Of diff.
icrcnt thermometers that a degree Of
heat Is whatever we are pleased to
make it, On Fahrenhcit's scale it is
one one hundred and cighticth of the
difference OF the temperatures of melt
ing ice and boiling water on the
scale of Celsius it is one one hundredth
Of the same difference, and on Rcau.
mur's it is one cighticth of this differ
encc. Other divisions of the scale
might be made, so that degree might
be of anymagnitude whatever. From
the manner of graduation it results
that nine Of Fahrcnhcit's degrees are
equal to five of Celsius, or four of
Rcaumur's. 1t is quite easy to con-
vert the degrees of one scale into tho
corresponding ones of another.
CORRECTING AND USING THE THERMOMETER.
The slow contraction of the glass
containing the mercury renders tho
thermometer after while incorrect.
1t forces the mercury higher up the
tube than it should be. To correct the
instrument, place it in melting ice and
water and observe how far the column
stands above the freezing point, then
lower the tube on the scale by an
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