The Plymouth Democrat. (Plymouth, Ind.) 1869-1941, 1870-11-17
THE Their MOMETER.
BY s. III. PEABODY, ". 4.


ANYBODY knows what thermometer
is 1t is a glass tube with a bulb at the
bottom; it has mercury in it, and hangs
fastened to lin scale behind the door.
People look at ii when it is very hot or
very cold, 20 see how much il will do to
fret. That's The common idea Let Us be
more precise. There is glass bulb, fill d
usually with mercury, sometimes with
colored alcohol, and, in fact, any liquid
would serve in some degree.
increased heat causes the liquid i'm the
bulb to expand, and the increased bulk
must find room for itself in the very fine
bore CT the tube attached This bore seems
- have considerable breadth. when viewed
in one direction, but if seen from the side
Is found TO be exceedingly thin
F low Is thermometer made? First. a
glasS-blower takes some melted glass on
the end of an iron tube, and upon one side
he adds small amount OF opaque white
glass, also melted. lie blows into the scft.
adhesive mass, the air forcing hollow
space in the centre.
When the glass is long bottle with
thick walls, another workman seizes the
bottom with pinchers, and then the two 90
quickly in opposite ways, pulling the soft
and the walls diminish in the same pro-
portion. so that the tube may be very fine
without closing. The patch of Opaque
White glass has also drawn out into
white strip. against which the mercury
may be more clearly seen. Although the
tube may be as much as twenty or thirty
feet long, only small piece from the mid
die Is just suited for a thermometer tube
The rest, if not used for other purpos, S. is
broken UP and melted again
y workman selects Il piece of proper
length, and heats one end in the flame of
lamp until the glass melts and closes then.
by blowing in the open end, and carefully
turning the glass in the flame he forms the
bulb upon the closed end. This REQUIRES
great skill, which is obtained only BIZ
much practice
The open end OF the tube is placed in
dish of mercury while the bulb is still hot
You understand at once that if the glass is
hot the air within is also hot, and there
fore rare As the bulb cools, the air con-
denses, and then the pressure upon the
surface Of the mercury in the dish forces
tho mnrnnry In ihrssugil The f,ne IlItc into
the bulb. When the tube has sucked up
all it can, il is inverted again, aHd held
over lamp until the mercury bOilS; the
vapor drives out the remaining air, the
open end is sealed III the flame, and the
thermometer is made
Now il must be fastened 10 a plate of
metal, or something equivalent, OH which
is scale of some Kind.
First, the tube is set into wa or that con
tails melted ice, and after standing awhile,
the place of the mercury Is marked as the
freezing point. Then il is placed in boil
ing water, and the place OF the boiling
point is found. The space b TIVE these
two points may be divided into as many
parts as We choose, and each may be-
called a degree, if we only understand
each other
Fahrenheit, a IIollander. in 1903 divided
the space into 1S2 parts, calling the frecz-
ing point - and the boili point PIP his
scale is used in Holland, England AID
America to this day Celsius, Swede,
divid, the space into 100 parts. and Reau
muir, 4 Frenchman, into eighty parts. Both
Celsius and Reaumur called the freezing
point 0. Occasionally large thermometers
have all the three scales upon the same
plate, SO that the observer may Use what
he pleases.
So then, when the thermometer indi-
Gates 1872 degrees by Fahrenheit's scale,
the mercury has passed over 10-1S0ths of
the space from the freezing to the boiling
point.
The size of the degrees between 30 de-
grees and PIP degrees is continued above
and below. The graduation in a mcrcurial
thermometer may be carried no higher
than eco, since mercury boils at that point;
nor more than 80 degrees below 0, since
mercury freezes there Thermometers
which Indicate greater cold are filled with
alcohol or cther.-LdHe Chi6f