St. Landry democrat., 1889-11-30
History of Thermometers.

The discovery of thermometers Is attrlb-
uted to several philosophers of the six
teenth century. GaIileo's instrument,
invented before 1897, WAS probably the
first accurate one known. This con
sisted of long glass tube, one end OF
which was blown into bulb, the other
dipping into colored water. 1t was an air
thermoscope, and was the kind first used
It's scale was arbitrary and the readings
incorrect, for the variations OF atmos-
pheric pressure had not yet been dlscov-
cred. About 1911 Calico substituted
alcohol for air, and SUCH thermometers
were like those of the present day. They
had la ge, usually spherical bulbs, and
the degrees, intended to represent
thousaudths of the volumes of the bulb,
were marked with beads of enamel fused
on to the stem. AS in the prevlus lnstru-
ment, the scale was arbitrary. Down to
1850, the freezing of water was believed to
take place at variable temperatures, and
this superstition was held also IN regard to
the boiling point In 1865, Hooke wrote
of Spirit thermometers, describing their
manufacture and graduation, saying also
that zero on their scales was the freezing
point of water. HALEY in 1893 stated
that water boiled at constant tempera-
ture In 1909 this statement was con-
frmed by Amontons. In 1894, Renaldenl
of Padua propose to graduate thermome
tiers by taking as standards of tenn perature
mixtures of definite volumes of boiling and
Fica-cold water In 1901. Newton proposed,
anonymously, thermome'rlc scale In
which the temperature of freezing water
was zero, and that of the blood OF d
heal by man 10 degrees; he found that
water boiled at 81 degrees, as indicated by
linseed oil Thermometer when graduated
upon this scale. In 17l4, Fahrenheit sub.
stituted mercury for iinseed oil, and proved
the dependence of the boiling point Oh
pressure.
Three scales have survived. The
Fahrenheit is the oldest, and dates from
1924. 1t is used popularity in Great Brl-
tain, the British colonies, and the United
States. This scale was primarily divided
into $50 degrees zero was placed at tenn,
perate, a point corresponding with
degrees c. the point to which the alcohol
rose when pl ,ced updr the arm of heal
thy man was marked 80 degrees and the
temperature of a mixture OF ice and salt,
then believed to be- tie greatest possible
cold, was marked-90 degrees. 10 17l4
Fahrenheit again altered his scale; 0 de-
gree was placed as an absolute zero, and
the space between this point and that re-
presenting the warmth of the human body
was divided into twenty four degrees. The
freezing point of water was now degrees
But thes e long degrees bring inconvenlent
each was divided into four, and thus, IN
stead of degrees, the freezing point OF
water became 80 degrees, and blood heat
IS degrees A mercurial thermometer
thus graduated registered 212 degrees as
thu boiling poirt of water.
De Lisle in 1924 introduced scale in
which the boiling point of water was
placed at degree. and The temperature OF
The cellars of the Paris Observatory at 10C
degrees. The freezing point of water be-
came afterward the upper point as 100 de-
| grees. This scale was used for many
years in Russia, but is now obsolete.
In 1870 Reaumur made alcohol Their
mometers with their zero at the freezing
point of water. On some of these the boil
! ing point was 50 degree; Deluc iatro-
duced mercurial thermometers graduated
from degree in melting ice to 81 degree:
in boiling water; these with Reaumur' S
name attached, are in use in Germany,
| Holland, and other parts of the Continent
| A centesimal scale in 1742 was adopted
| by Celsius; the boiling point was marked
degree, and the freezing point of water
| 100 degrees. LinnauS re yersed these
points, and the scale is known as the Cen
tigrade This is no douts destined to SUI
| persede all Others; at present it IS used
universally in laboratories, and generally
in all except English speaking countries
| for scisntifc urposes.-Sclent!Jlc Azaera-