llic chips. Rumford describes these
experiments at length, and they are conclusive.

He then designed a cylinder for the express purpose of generating heat
by friction, by having a blunt borer forced against its solid bottom,
while the cylinder was turned around its axis by the force of horses. To
measure the heat developed, a small round hole was bored in the
cylinder for the purpose of introducing a small mercurial thermometer.
The weight of the cylinder was 113.13 pounds avoirdupois.

The borer was a flat piece of hardened steel, 0.63 of an inch thick,
four inches long, and nearly as wide as the cavity of the bore of the
cylinder, namely, three and one-half inches. The area of the surface by
which its end was in contact with the bottom of the bore was nearly two
and one-half inches. At the beginning of the experiment the temperature
of the air in the shade, and also that of the cylinder, was 60 deg. Fahr. At
the end of thirty minutes, and after the cylinder had made 960
revolutions round its axis, the temperature was found to be 130 deg..

Having taken away the borer, he now removed the metallic dust, or rather
scaly matter, which had been detached from the bottom of the cylinder by
the blunt steel borer, and found its weight to be 837 grains troy. "Is
it possible," he exclaims, "that the very considerable quantity of heat
produced in this experiment--a quantity which actually raised the
temperature of above 113 pounds of gun-metal at least 70 deg. of
Fahrenheit's thermometer--could have been furnished by so inconsiderable
a quantity of metallic dust and this merely in consequence of a _change_
in its capacity of heat?"

"But without insisting on the improbability of this supposition, we have
only to recollect that from the results of actual and decisive
experiments, made for the express purpose of ascertaining that fact,
the capacity for heat for the metal of which great guns are cast is _not
sensibly changed_ by being reduced to the form of metallic chips, and
there does not seem to be any reason to think that it can be much
changed, if it be changed at all, in being reduced to much smaller
pieces by a borer which is less sharp."

He next surrounded his cylinder by an oblong deal-box, in such a manner
that the cylinder could turn water-tight in the centre of the box, while
the borer was pressed against the bottom of the cylinder. The box was
filled with water until the entire cylinder was covered, and then the