wo were
actually employed. Heat may thus be produced merely by the strength of a
horse, and, in a case of necessity, this heat might be used in cooking
victuals. But no circumstances could be imagined in which this method of
procuring heat would be advantageous, for more heat might be obtained by
using the fodder necessary for the support of a horse as fuel."

[This is an extremely significant passage, intimating as it does, that
Rumford saw clearly that the force of animals was derived from the food;
_no creation of force_ taking place in the animal body.]

"By meditating on the results of all these experiments, we are naturally
brought to that great question which has so often been the subject of
speculation among philosophers, namely, What is heat--is there any such
thing as an _igneous fluid_? Is there anything that, with propriety, can
be called caloric?

"We have seen that a very considerable quantity of heat may be excited
by the friction of two metallic surfaces, and given off in a constant
stream or flux _in all directions_, without interruption or
intermission, and without any signs of _diminution_ or _exhaustion_. In
reasoning on this subject we must not forget _that most remarkable
circumstance_, that the source of the heat generated by friction in
these experiments appeared evidently to be _inexhaustible_. [The italics
are Rumford's.] It is hardly necessary to add, that anything which any
_insulated_ body or system of bodies can continue to furnish _without
limitation_ cannot possibly be a _material substance_; and it appears to
me to be extremely difficult, if not quite impossible, to form any
distinct idea of anything capable of being excited and communicated in
those experiments, except it be MOTION."

When the history of the dynamical theory of heat is written, the man
who, in opposition to the scientific belief of his time, could
experiment and reason upon experiment, as Rumford did in the
investigation here referred to, cannot be lightly passed over. Hardly
anything more powerful against the materiality of heat has been since
adduced, hardly anything more conclusive in the way of establishing that
heat is, what Rumford considered it to be, _Motion_.

VICTORY OF THE "ROCKET" LOCOMOTIVE.

[Part of Chapter XII. Part II, of "The Life of George Stephenson
and of His Son, Robert Stephenson," by Samuel Smiles New York,
Harper & Brothers, 1868.]

The works of the Liverpool and M