He then determines the "_celerity_" with which the heat was generated, summing up thus: "From the results of these computations, it appears that the quantity of heat produced equably, or in a continuous stream, if I may use the expression, by the friction of the blunt steel borer against the bottom of the hollow metallic cylinder, was _greater_ than that produced in the combustion of nine _wax-candles_, each three-quarters of an inch in diameter, all burning together with clear bright flames. "One horse would have been equal to the work performed, though two 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.]