The Wichita daily eagle. [volume] (Wichita, Kan.) 1890-1906, 1892-05-14

They Are Made Very Accurately, and.
Though Quickly, Pass Through Nine
teen Pairs of Hsnds-The Different
Processes of the Instruments
The making of Thermometer may be
either delicate scientific operation, or
enc of the simplest tasks Of the skilled
mechanic, according 10 the sort of Their
mometer made With the extremely
sensitive snd infinitely accurate instru-
ments designed for scientific uses great
care is taken, and they are kept in stock
for months, sometimes for years, to be
compared and recompared with instru-
ments that are known TO De Trustworthy
But so much time cannot be spent over
the comparatively cheap thermometers
IN common use, and these are made rap
idly, though always carefully. The
method of manufacture has been so sys-
tematized within a few years that the
very cheapest thermometer should not
vary more than a fraction of a degree
from the correct point.
Whether the thermometer is to be
charged with mercury or alcohol: wheth-
er it is TO be mounted in frame Of
wood, pressed TIN or brass, the process
Is substantially the same. Mercury is
generally used for scientific instruments.
but most makers prefer alcohol, because
it is cheaper. The alcohol Is colored
red with an aniline dye which does not
fade.
The thermometer maker buys his glass
tubes in long strips from the glass fac
tories. The glassblower on the premises
cuts these tubes 10 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. aud
the tubes stand for twenty-four hours.
On the following day another work.
man holds each bulb in turn over a gas
jet until the colored fluid. by Its expan-
sion, entirely fills the tube. II then
goes back into the hands of the glass
blower. He closes the upper end and
turns the tip backward to make the lit
tie glass hook which will help keep tbs
tube IN place in the frame.
MARKING The TUBES.
The tubes now rest until some hun
dreds of them, perhaps thousands, are
ready. Then the process of gauging be-
gins. There are no marks whatever on
the tube, and the first guide mark TO be
made is the freezing point, 80 degs
Fahrenheit. This is found by plunging
the bulbs into melting snow. No other
thermometer is needed for guide, fer
melting snow gives invariably the exact
freezing point. This is an unfailing test
for any Thermometer whose accuracy
NAV be suspected But melting snow L.
not always TO be had, and little ma
chine resembling a sausage grinder Is
brought into use. This machine shaves
block of ice into particles. which an
swer the purpose as well as snow.
When the bulbs have been long enough
in the melting snow a workman takes
them one by one from their icy bath.
seizing each so that his thumb nail
marks the exact spot 10 which tho fluid
has fallen. Here he makes a scarcely
percepGble mark upon the glass with q
fine file, and goes on 10 the next
The tubes, with the freezing point
marked on each, now go into the hands
of another workman, who plung@s them,
bulb down, into vessel filed with
water kept constantly at 81 dogs.
A standard Thermometer attached 10
the inside Of this vessel shows that the
temperature of the water Is correct
Another tiny file scratch Is put at "a.
Then a third workman plunges the
bulbs into another vessel OF water kept
constantly at SO. This is marked
like the others, and the tube Is now sup
piled with these guide marks, each
81 dogs. from the next. Il small tab
Is then attached &c each tube, on which
its number Is written-for, owing 70 I'M
avoidabls variations in the bore of the
tube, each one varies slightly from the
Others
MARKING THE CASES.
With its individuality thus established
the tube goes into the hands of mark
er, who fits its bulb and hook into the
frame it is TO occupy. and makes slight
scratches on the frame corresponding 10
the 81, ca and 80 degree marks On the
tube. The frame has number CORE
spending with the number Of the tube.
and the tube is laid away In rack amid
thousands.
The frame, whether it be wood. TIN
or brass. goes TO the gauging room,
where 1t Is laid upon a steeply sloping
table, exactly in the position marked for
a Thermometer Of that size. The %, O.
and e6 degree marks must correspond
with the marks upon the table. II they
do not, the error IN marking Is detected
and the frame Is sent back for correc-
ton
A long. straight bar Of wood or metal
extends diagonally across the table from
the lower right hand corner 70 the upper
left hand corner On the night this
works upon a pivot and On the left 1t
rests IN a ratchet. which lets u ascend
or descend only one notch az time
That notch marks the exact distance Of
2degs- With the three scratches already
made for beAsss the marker could hardly
make a mistake IN TIE degrees If De tired
The marks made upon the frame or
case are all made by hand with geo
metro pen and india INK if the frame Ii
Of wood. and with steel dies II u "a q
metal The tub4 tearlng the correspond
ing nun Der Is rseKt attached 20 the frame,
and the Thermometer = ready for the
market without further testing. some
makers Use only two guide marks, but
the b,zst makers Use three.
Ia t1s process q Manufacture the
ordinarv Thermometer goes tnro8gh the
hands Of nineteen wo-kTasD. half 81