The morning call., 1893-01-29
ABOUT THERMOMETERS.
Everybody Wants One Nowadays.
How They Are Made.
N

How They Are Made.
New YORK News,
Thermometers have entered into the
household economy in a way that is sur
pTisng. Thermometers are good thing 10
have around, for else how can you tell
whether 1t is hot or colo? It is a silver
dollar 10 d0ughnut that half the popula-
tion take their temperature from them, Just
as they do, at times, take their barometric
information from Mr.. Dunn and the news
papers.
The making OF thermometer may be
either a delicate scientific ogeration or one
Of the plest tasks of the skilled mechanic,
according to the sort Of thermometer You
want With The extremely sensitive and
infinitely accurate instruments des gned for
gclenti6c uses great care is taken, and they
are kent in stock for months, sometimes for
years, 10 be compared and recompared with
instruments that are known 20 be ITust-
worthy.
But so much time cannot be spent over
the comparatively cheap thermometers in
common use These are made rapidly,
though always carefully. The method Of
manufacture has been so systematlZed
within recent years that the very cheapest
thermometer should not vary more than the
fraction Of & degree from the correct point.
Whether a thermometer is to be charged
with mercury or alcohol; whether it's to be
mounted in a frame Of wood, pressed TIN or
brass. the process Is substantially The same.
Mercury is generally used for scientific in
strumeuts, but most makers prefer alcohol.
because it is cheaper. The alcnaOl Is cOlOTed
red with an auillpe dye which does not
fade.
The thermometer maker buys his glass
tubes IN long stripes from the glass fac
tories. The glass-bloweT cuts these tubes 10
the proper lengths, and with his gasjet and
bioWpipe makes the bulb on the lower end.
The bulbs are then flied with cOlOred alco-
moi 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 cOlored fluid by its expansion
fills tie tube. 1t is taken back TO the glass
blower. he closes the upper end aud turns
the top back ward TO make the little glass
hook which will help deep the tube III 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 what
ever on the tube and the first guide-mark
10 be made is the freezing mark.
Tits Is formed by plungng the bulbs into
melting snow No other thermometer is
needed for a guide, for melting snow gives
Invariably the exact freezing point. This
is an uniaiing test for any thermometer
whose accuracy may be doubted. Melting
snow Is not always TO be had. and a little
machine resembling age-gTinder Is
brought into use. This machine shaves a
block of Ice ins0 particles, which answers
the purpose as we'll a. snow.
When the bulbs have been long enough
In this melting snow a workman takes them
enc By one from their icy bath, SEEING each
one 80 that his thumb-nail marks the exact
spot to which the fluid has fallen. Here he
makes q scarcely DeTceptible mark upon the
glass v it'll fine file and goes on to the next.
The tubes with the freezing point marked
on each now 60 into the hands Of another
workman, who Dlunges them. bulb down,
into vessel filed with water kept con-
stantly 81 g. degrees. 4 standard ther-
mOmeter attached 10 the inside Of this yes
SCI shows that the temperature Of the water
IS correct. Another tiny file scratch Is
made at 64
a third time the bulb Is showed into
water kept constantly at 96, which, like the
others. is marked. A ia is affixed to each
tube. 1t is then given over to the marker,
who fits the bulb and hook into a frame,
and makes slight scratches corresponding
10 the o. g. and SO marks. 1t is next given
over TO workman who cuts the degree
marks.
Altogether it takes nineteen workpeople
to make q thermometer. Nine are females.