The L'Anse sentinel. (L'Anse, L.S., Mich.) 18??-current, 1892-04-16
ABOUT THERMOMETERS.
TO MAKE a FINE ONE REQUIRES
NINETEEN PERSONS.
Even tho Cheapest Their momcter I,
Made So Carefully Tn 1t 1t shouid
Vary From the Correct
Point Very Little.

The making o. thermometer may
be either delicate scientific opera.
ton. or one Of the simplest tasks OF
the skilled mechanic. according to
the sort OF thermometer made With
the extremely sensitive and infinitely
accurate instruments 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 instruments that
are known to be trustworthy. But SO
much time cannot be spent over the
comparatively cheap thermometers in
common use. and these are made rap.
idly though always care fully. The
method OF manufacture has been so
systematized within few years that
the very cheapest thermometer should
not vary more than a fraction OF de-
gree from the correct point according
to the New York Sun.
Whether the thermometer Is to be
charged with mercury or alcohol;
whether 1t Is to be mounted in a
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 1t 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 factories The glass blower on
the premises cuts these tubes toSthe
proper lengths and with his gas JET
and blowpipe makes the bulb on the
lower end. The bulbs are then tilled
with colored alcohol. and the tubes
stand for "a hours.
On the following day another work.
man holds each bulb In turn over a
gas jet until the colored fluid. by its
expansion. entirely fills the tube. II
then goes back into the hands of the
glass Shower. He closes the upper
end. and turns the tip backward to
make the little glass hook which will
help keep the tube In place in the
frame
The tubes now rest until some hun.
dreds OF them. perhaps thousands 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 point 80
! degrees Fahrenheit This is found by
plunging the bulbs into melting snow.
No other thermometer is needed for a
guide for melting snow gives invari
ably the exact freezing point This Is
an unfailing test for any thermometer
whose accuracy may be suspected.
But melting snow is not always to be
had. and little machine resembling
a sausage grinder is brought into use.
| This machine shaves a block OF Ice
into particles which answer the pur
pose as we'll as snow.
| When the bulbs have been long
enough IN the melting snow a work
man takes them one by one from theil
icy bath. selling each one SO that hi.
thumb nail marks the exact spot tc
which the fluid has fallen. Here he
makes scarcely perceptible mark
upon the glass with fine file anC
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 a yes
sci filed with water kept constantly
at "a degrees A standard thermome
attached to the inside of this vesse
shows that. the temperature of the
water is correct Another tiny file
scratch is put at GA.
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 nov
supplied with these guide marks
each so degrees from the next A
small tab is then attached to each
tube on which its number Is writer
for. owing to unavoidable variations
In the bore Of the tube each one
varies slightly from the others
With its individuality thus estab
lished the tube goes into the hands o
a marker. who fits its bulb and hool
into the frame it Is to occupy. ant
makes slight scratches ON the frame
corresponding to the so. g. and 81
degree marks on the tube. The fran,
has number corresponding with tn,
number OF the tube and the tube Il
laid away in a rack amid thousands
The frame whether it be wood, tin
or brass. goes to the guageing room
where it is laid upon steeply slopine
table, exactly in the position marked
for thermometer of that size. The
| 80. GA and SO degree marks must cor
respond with the mark upon tn,
table. II they do not tire error IL
making is detected. and the frame Il
sent back for correction.
A long. straight bar Of wood Of
metal extends diagonally across tn,
table from the lower right-hand cor
ner to the upper left-hand corner. Or
the right this works upon pivot
and on the left 1t rests in ratchet
which lets It ascend or descend only
one notch at a time. That motel
marks the exact distance OF tive
degrees. With the three scratche
already made for basis tho marke
could hardly make a mistake in tn,
degrees II he tried.
The marks made upon the frame O.