The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1883-12-22
MAKING THERMOMETERS.
Some Material and Considerable Trouble fol
Fifteen Cents.


"First-cass thermometers for fifteen
cents!" called out a man who stood in the
lower part of Broadway, with large basket
of thermometers in front of him. Here is
a good chance to buy perfect register OF at
mospherc temperature for the small sum of
a dime and half. Step forward, gentlemen,
and embrace your opportunityP
The thermometers were inclosed in neat
japanned tin cases, and the scales were silver
plated and marked in black. Some of the
tubes held mercury, and some held colored
alcohol.
II cannot comprehend how thermometers
can be manufactured for that price" Their
mometer-maker said Where can the profit
be? You have no idea of the great trouble
and the amount of time that it takes to make
an accurate thermometer. / know that Their
mometers can be bought throughout the
city anywhere from fifteen cents up, and l
must say, also, that many of them are good
thermometers. These cheap thermometers
are not manufactured in this city. They
come chiefly from Connecticut, where there
are several large factories which turn them
out in vast mum bers. "
"Why are accurate thermometers so costly
to make%'
'In the first place, we buy the glass tubes
and test them. According to my experience,
only one out of every six is fit to put into
thermometer"
How are the tubes tested?'
by drawing into them a short column of
mercury, and measuring its length at differ
ent points with pair of divlders. II is alb
solutely necessary that the bore OF the ubes
be uniform. Then the bulb has to be blown
and filled with mercury. The air is driven
out of the tube by heating the mercury to
boiling point, and then putting tip Of seal
ing wax on the open end. The amount of
mercury necessary for the tube is regulated
by vaporizing it off. Then the open end of
the tube is closed by heating the glass The
next thing is to make the scale"
Must a fresh scale be made for each Their
momcter?"
Certainly. To make the scale it is neces-
sary to have at least two points on the Dubbed
tube which holds the mercury. The points
usually selected are the freezing point and
boiling point of water. For the former the
bulb is surrouned by ice, and for the latter
it is placed in boiling water From these
points the scale is made. Each scale is
stamped out by hand. Afterward the Dubbed
tube is fastened to the scale, which is on a
sill ver-plated strip of brass. 1t is then fast
ened in tin case"
Are the fifteen.cent Thermometers made
in this way?'
II suppose that they must be- and it is for
this reason that don't see where the profit
comes in,"
"Is there no other way of grading a Their
mometer than by putting the bulb in ice and
in boiling water?'
Eyes. The points may be obtained by
putting the bulbs in water the temperature
of which is told by standard thermometer
kept especially for that purpose. That meth
cd is often used"
rs mercury better than colored alcohol in
thermometers"
ut is, except where the thermometers are
wanted for measuring extreme cold. Mer-
curry can be frozen solid but it is impossible
to freeze alcohol. Experiments have been
made which show that the most intense cold
known will only have the effect of making
the alcohol oily in its appearance. Mercury
withstands more heat before it boils than
alcohol does, for alcohol boils at a lower
temperature than water. The kind of Their
mometers which have been speaking Of are
those which are most commonly used"