Iron County register. [volume] (Ironton, Iron County, Mo.) 1867-1965, 1893-02-23
ABOUT THERMOMETERS.

everybody Wants One Nowadavs ana Me-
we Sel How They Are Made.
The making of Thermometer NAV h
Neasner delicate scientific operation. O,
one OF the simplest tasks of the slriiled
mechanic, according to the sort Of
thermometer you want. With the er
tremely sensitive and infinitely accurate
instruments designed for scientific uses
great care is taken, and they are kent
IN stock Tor months, sometimes for
years. to be compared and recompared
with instruments that are known to be
trustworthy.
But so much time can not he sren.
over the comparatively cheap Their
mometers In common use. These are
made rapidly, though always carefully.
Inc method of manufacture has been
$50 systematized within recent wears
that the very cheapest THERMOMETERS
should not vary more than the fraction
OF degree from the correct point.
Whether the Thermometer is to be
charged with mercury or alcohol:
whether it is to be mounted in a frame
OF wood. pressed tin or brass, the proc
~ess Is substantially the same. Mercury
IS generally used for scientific instru-
ments. but most makers prefer alcohol
because it is cheaper. The alcohol Is
-coiored red with an aniline dye which
does not fade.
Inc thermometer maker buys his
glass tubes in long strips from the glass
factories The glassblower cuts these
tubes to the proper lengths, and with
his gas jet and blowpipe makes the
bulb on the lower end. The bulbs are
then filed with colored alcohol and the
tubes stand for twenty-four hours.
On the following day another work.
man holds each bulb in turn
over the gas jet until the col
-ored fluid by its expansion fills
the tube. 1t is then taken back to the
glass-blower. He closes the upper end
and turns the top backward to make
the little glass hook which will help
keep the tube in place in the frame
The tubes now rest until a great
number of them are ready. Then the
process of gauging begins. There are
no marks whatever on the tube, and
the first guide mark to be made is the
freezing mark.
This is formed by plunging the bulbs
into melting snow. No other ther-
mometer is needed for a guide, for
melting snow gives Invariably the exact
freezing point. This is an unfailing
test for any thermometer whose ac-
~curacy may he doubted. Melting snow
is not always to be had, and a little
machine resembling sausage grinder
is brought into use. This machine
shaves a block of ice into particles,
which answers the purpose ss well as
snow.
When the bulbs have been long
enough in the melting snow, work
man takes them one by one from their
icy bath, selling each one SO that his
thumb nail marks the exact spot to
which the fluid has fallen. Here he
makes a scarcely perceptible mark up
ON the glass with fine file and goes on
to the next.
The tubes with the freezing point
marked on each now go into the hands
of another workman. who plunges
them, bulb down, into vessel filled
with water kept constantly at sixty
four degrees. A standard thermome-
ter attached to the inside of this yes
sci shows that the temperature of the
water is correct. Another tiny file
scratch is made at sixty-four.
A third time hesbulb is showed into
water kept constantly at ninety-six.
which. like the others, is marked. A
tab is affixed to each tube. It is given
over to the marker, who fits the bulb
and hook into frame, and makes
slight scratches, corresponding to the
thirty-two, sixty-four and ninety-six
marks. 1t is next given over to a
workman, who cuts the degree marks.
Altogether, it takes nineteen work
people to make a thermometer. Nine
are females. Any time you have time
you could not spend half day more
pleasantly than looking at the making
of athermometer.-N.Y Y. News