er than in a vessel heated a little above the boiling point, from
the reason that in the red hot vessel no _real contact_ takes place
between the vessel and the water. At the place where the two ought to
touch, steam is formed quicker than it can escape, which steam prevents
the contact between vessel and water; therefore, as no real contact
takes place, the heat from the vessel can pass into the water but
slowly, viz., in the proportion as it works itself through the layer of
steam, which in itself is a bad conductor. Just so in Prof. Carnelley's
experiment: The heated glass vessel will convey heat to the ice only at
those points where it touches the ice; at those points at once a
formation of vapor takes place, which prevents an intimate contact
between the glass and the ice, so that they do not really touch each
other, consequently the heat can pass into the ice but slowly, having to
work its way through the thin layer of rarefied vapor between the two.
As soon as pressure is admitted by admitting atmospheric air, vapors can
no longer form; an intimate contact will take place between the glass
and the ice, and consequently the heat be conveyed over quick enough to
make the ice melt away rapidly.

The professor's experiments, therefore, so far as published, do not
prove anything to justify his strange conclusion. It is perfectly true
that in a vacuum of less than 4.6 mm. mercury pressure, no amount of
heat will melt ice, all heat that can be conveyed to the ice being
absorbed by vaporization. But before crediting the professor's further
conclusion, that ice can be heated much above the freezing point, he
must actually produce "hot ice," not only a hot vessel containing ice.
N. J.

Brooklyn, N. Y., October 25, 1880.

* * * * *

SCHOOLS OF INVENTION.

The school of invention has not yet been established, but its germ is
growing in the mechanical schools. This school, according to Hon. W. H.
Ruffner, in _Va. Ed. Journal_, will educate men, and women too, for the
special career of inventing new things. Why not? We already have
something closely analogous in schools of design, where the pupil is
trained to invent new forms or patterns, chiefly of an artistic or
decorative character. The same idea will be applied to the invention of
machinery, or improvements in machinery, or the adaptation of machinery
to the accomplishment of special ends. Inventions usually spring from
individ