Evening star. [volume] (Washington, D.C.) 1854-1972, 1889-01-04
FACTS ABOUT THERMOMETERS.
The Common Mercury Tube with the
Fahrenheit Scale and other Varieties.

Jhe common Mercury Tube with the
Fahrenheit Scale and other Varieties,
Prom the " y. Mail and Express.
Very few Of the thousands OF neonle who
consult the thermometer during periods of ex-
treme temperature, summer or winter. are en-
tirely satisfied with the results of their obser-
vations. They almost invariably think it colder
or warmer, as the case may be, than it really
is, and generally are disappointed that it is not
so. There seems to be a sense of grim salts
faction derived from reveling in extremes. and
a weatherwise son of humanity rejoices when
the Thermometer breaks the record"
By what is a thermometer? Simple little
thing as it appears, not everybody can answer
the question. Indeed its construction and the
why and wherefore" of its movements ND and
down are but specifically known 70 the major
ity Of people. To learn something about il
visited some Of the establishments in this city
where thermometers of all sorts and sizes are
made and sold. and obtained number of
points about them which will T. 10th instruc-
tive and interesting.
The mercury thermometer is almost uniyers-
ally used "a a temperature indicator in the
temperate zones. The mercury or quicksilver.
used for the purpose is extracted from cinnibar
ore which is mined in California and Mexico
After undergoing refining process il is packed
in cans holding from one to five pounds each.
and sells at Wholesale at present for about S5c
pound.
Mercury, however, Is not used in thermom-
eters intended for very cold climates. be-
cause II freezes at a temperature of 40 degrees
below zero, though Ii answers all purposes for
exceedingly high temperatures. When Their
mOmeters are intended for use in frigid zones
spirits have to be substituted for mercury IL
is not known at what degree of cold the spirit
Thermometers will freeze and become useless.
for cold Of sufficient intensity has never vet
been measured where a spirit thermometer has
failed TO work. even in a temperature of 10 de-
grees below zero.
The spirits used in thermometers are ex-
tracted in the usual way from wood potatoes
and grain and are purely colorless The red
color noticed is impaired by aniline dyes and
this is done only for the purpose of rendering
the spirits in the tube more easy to see The
addition of the eoloring matter interferes
somewhat with the sensltlveness of the fluid
to atmospheric changes. and is not added to
the pure white spirits contained in tubes of
thermometers used for scientific purposes. and
where the greatest accuracy and most minute
variations are of great Importance. At best
spirit thermometer Is not equal to a thermOm-
eter in which mercury is used. because ii is not
so sensitive and does not so readily respond to
changes of temperature.
The length OF the glass tube has nothing
whatever to do with the accuracy of the indi-
cations of a thermometer. and although some
are scaled TO indicate a temperature as high as
COO degrees above zero, the tube is made long
only to afford surface for a scale upon which to
strument an inch long, carefully made, is just
as accurate and responsive to variations of
temperature as the long one; but it would re-
quire microscope to make the readings.
The smallest and most sensitive thermometer
made. and the one having the greatest number
of subdivisions on the scale, recording ffths of
a degree, is that used by the physicians for
taking temperatures of the human body. The
sensitiveness of thermometer increases with
the relative increase in the size of the bulb
no Ipb (Sai xaSlt bar,
eters used by the United States signal service
and at the various meteorological ob5ervatOries
have the bulbs filed with mixture of ether
and alcohol instead of mercury or spirits.
A thermometer is made and adjusted by
heating water to the boiling point. placing the
glass bulb in the boiling water and then filling
ii with mercury Spirits or ether till il rises in
the tube to 212 degrees-the boiling point. The
freezing would answer the purpose equally
well for adjusting thermometer, but it is not
used, because a temperature of 212 degrees is
much more easily obtained than one of 80 de-
grees.
Special thermometers of great accuracy and
extreme sensitiveness are made for special Dur
poses. Thus thermometer with scale run
ming as high as GOO degrees is made for taking
the temperature of ovens, and the chiefs of no.
tells and restaurants, by computing the number
Of pounds to piece of meat and the tempera-
ture of the oven, can tell how long to allow it
TO cook and know exactly when it is dome to
turn. Brewers also use a specially made in
strument with a register running as high as
$50 degrees for taking temperatures of their
mash-tubs, while confectiOners use a thermOm-
eter indicating as high as $50 degrees to ascer-
tain when their candy has been boiled to a suf-
hciently high degree.
There are three thermometrical scales in gen.
eral Use in different parts of the world All
English-speaking peoples make use of a scale
invented by German by the name of Fab
renheit, and named after him. The Germans
tell whether II Is warm or cold by scale in
vented by and named for a Frenchman named
Reaumur, while the French, Italians, and 9TH
ers ascertain the temperature by a scale
founded upon the metric system and called
Centigrade. The following table shows the
relative systems compared with each other at
the boiling and freezing points:
Water Water
Freezes. Boils
Fahrenheit .(deg) 80 212
Keaunur. -................. o so
NCntibAauc... " lUU
The Centigrade scale is used by scientists ex-
clusiyely as being the most naturally arranged
The division being based upon the metric, or
decimal system, the figures are much more
n -