The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1901-04-21

which are successfully employed in pot
terry works or where large kilns are used.
At one such place several hundred dollars
worth of fine ware ruined regularly
each week because the kiln was sallowed
to get too hot or to fall below the exact
temperature required. The eye OF the
man in charge had been the pyrometeT,
but carefully trained as he was in the
management of such "A furnace, 1t was
discovered by the tests made from the
institute. that he was unable to keep the
kiln from day TO day within 800 or even
400 degrees of what experience had shown
was the necessary temperature. One hum
dred degrees of variation was allowable
without serious damage. but 400 meant
the loss of the whole charge. Yet this
workman, in spite of his inability TO cs-
innate whether the kiln as a whole, was
at 1900 or 5000 degrees, could always tell
within % degrees whether the top or the
bottom was the hotter Optical promoters.
however. give mechanical aid to the human
eye in various ways In one instance the
temperature is judged by the brilliancy
of the object in comparison, through
telescope, with "a standard lamp, and in
second by exactly testing the color. on the
perature of the object rises, the red ele-
ments being distinguished by means of r
polariscope.
But pyrometery is concerned not only
with extreme heat but with extreme cold.
In this connection ii is interesting to note
that as extreme heat is measured by the
eye so extreme cold may be measured by
the ear by the use of an instrument called
ss+1,, ar thno -hna rar
consists of coil which is exposed to the
temperature that one wishes TO ascertain;
and pair Of wires which connect with an
electrical measuring device, part of which
is a telephone attachment The instrument
is particularly useful for refrigerating
plants, since the temperatures of various
chambers may be ascertained from a sim
gle station without the necessity of visiting
them.
SOME OF THE EXPERIMENTS.
Experiments in heat-measuring devices at
the Institute of Technology connect them
selves with other experiments having to do
with the effects of heat on various SUBJ
stances. For instance, steel bars are placed
in an electric furnace, which, with its
white-heat-proof covering is about large
as an umbrella stand, and kept there for
a
which is accurately controlled and con-
stantly recorded. When the bars taken
out they are turned down a lathe and
broken in a breaking machine to show
their structural condition The nonconduc-
tive covering of the furnace is in itself an
interesting subject of study and one that
in its application TO the covering of steam
pipes has received much attention from
T,of ,Io&
properly covered furnace heated to sew
eral thousand degrees may be taken in the
bare hands while melted platinum is poured
out of its mouth. Incidental also to the py-
rometric work is the measurement of the
heating power of fuel. Various methods are
here used-the most successful being called
the bomb method" The fuel which is to
be the subject of the experiment is Enclosed
in a strong steel or bronze bomb with
enough oxygen to burn it completely. This
is set in can of water with a delicate
thermometer-the "calorimeter' described
above-which records the amount of heat
given out. This method, which has recently
been improved by Professor Norton, re-
quires great care, since the bomb is
charged with oxygen at pressure of twen-
ty-five atmospheres. IT is part of kind
of work for which there is a growing de-
mand and for which the attention of a
trained physicist is required. Fuel tests.
indeed, become constantly more necessary
now that coke is coming into extensive
use; since a slight variation during the
process of coke making may change the
heating power of fuel from the same ovens
in contrast with the fact that coal from
the same source varies but little.