Evening capital journal. (Salem, Or.) 1888-1893, 1888-06-11
THE THERMOMETER.
AN INSTRUCTIVE SKETCH ABOUT
A VERY USEFUL INVENTION

Use Throughout the Worid-Thc Iahr.
eDheit Thermometer-The Zero Point.
Method Of veriGcation.
The thermometer in its crude form was
invented by a Hollander named Cornelius
Drebbel who, It appears, made the first in
strumeut, which be called a cheat meas
urer, in the year l63S His Thermometer was
simple enough, and had numerous defects,
consisting Of a glass ball at the top Of a long
tube, the lower and open end being placed
In a vessel filed with water, colored by So
luton Of nitrate Of copper. This instrument
was improved upon, and its defects gradually
removed by others; but il was HALEY. the
famous English astronomer, who first pro-
posed the use Of mercury as a fluid for the
Thermometer.
There are now three kinds of thermometers
in common use throughout the world: but the
form invented by Professor Daniel Fahren-
heit an ingenious German in the year 1909,
and from whom the instrument has been
named, is the one generally employed in this
country, and with which nearly every intel
ligent family in the land is provided, though
the "centigrnde Thermometer" is really the
most convenient and is now adopted in all
countries as the standard scale for scientific
reference and like the metric system, its
general use in this country is doubtless merely
a question of time.
Mercury boils and vaporizes at a tempera-
ture OF Gj2 dess Fahrenheit and for obtain
ing any higher temperature than this a me-
tallic instrument called the pyrometcr is
made use Of, but its indications are unreli-
sble. and yet il remains to discover some
more accurate method of measuring degrees
Of heat higher than 600 degs. by the Fahren-
heit Thermometer At a temperature of 80
dcgs. below zero mercury freezes and be-
comes solid mass malleable under the ham,
meri and for lower temperatures, pure alco-
hol spirits Of winc) colOred red with car
mine, is usually employed, but as in the case
of the pryometer, its indications cannot be
depended upon for accuracy. Fahrenheit
was not slow 20 recognize tho advantages
possessed by mercury as a fluid for the tube
of the thermometer Mercury, as an excel
lent conductor OF heat, is vastly more sus-
coptiblc 20 the changes of temperature than
nll other fluids IL is much more easily OBJ
tanned In perfectly pure state than alcohol,
which, even when prepared with the greatest
care, often contains air as well as other ad-
and alcohol is sometimes rendered
thick by great degrees Of cold, and under the
higher degrees st heat it expands excessively F.
and ununiformly
THE ZERO POINT
In the Fahrenheit thermometers the space /.
between the freezing and boiling point Of |
water is divided into $50 equal parts or ce- /.
5rees, the former being 81 dess. and the latter /.
5l2 degs. above zero, which was so called hy |
.he inventor from the fact that he supposed |
L 20 indicate the point Of absolute cold, or |
The very lowest degree that could be pro- |
iucod and measured by any instrument But /
-ho lowest degree OF cold possible to be OBJ |
.ainod Is now estimated TO be 523 degs., and |
Tho greatest artificial cold over produced is |
l3 degs by the Fahrenheit Thermometer |
The zero point OF a thermometer does not in |
ilcato the total absence of heat as commonly /
supposed and the term seems TO Imply, for an
absolute zero Of temperature has never yet
leen attained, and has only been approx
natoly determined, though il is considered
convenient as an ideal starting pont.n The
Gro OF n Fahrenheit Thermometer is the
emperaturo of a mixture Of ice and common
alt, which is usually employed in the opera
ion Of freezing ice cream.
Tho zero point OF a thermometer should al
Ways be carefully verified, unless the instru-
hont is known 20 he correct. To do this inn
nersc the bulb IN a vessel filled with snow or
ounded ice, and press slightly a layer of SOW
raj inches around it, So that the stem. which
hould be exactly perpendicular, is covered
Nth snow as high as the freezing point on
ho scale Do this in a room, the temperature
( which Is above the freezing point, as that
oiut indicates the temperature OF melting
now, Then in about half an hour read it,
lkmg caro- 20 have the eye exactly perpen-
ocular % the column Of mercury, and mov-
ig the Thermometer freely about iu the mix
are. In case the top OF the mercury and
lc trcy sing point ON the scale do not cor
'Spond, note the difference Some nstru.
lonts are So constructed as 20 admit Of loas-
ming tho srroWs and sliding the glass tuLa
oldng the mercury up or down "a distance
luivalcut to The error but il is not advisa-
10 to make frequent mechanical changes OF
Ms kind. Tho correction above Indicated
lould be- applied 10 each reading OF tho
ale Arthur X. Barrett In Detroit Fce
rvsS