[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 Manchester Railway were now approaching completion. But, strange to say, the directors had not yet decided as to the tractive power to be employed in working the line when open for traffic. The differences of opinion among them were so great as apparently to be irreconcilable. It was necessary, however, that they should, come to some decision without further loss of time, and many board meetings were accordingly held to discuss the subject. The old-fashioned and well-tried system of horse-haulage was not without its advocates; but, looking at the large amount of traffic which there was to be conveyed, and at the probable delay in the transit from station to station if this method were adopted, the directors, after a visit made by them to the Northumberland and Durham railways in 1828, came to the conclusion that the employment of horse-power was inadmissible.
Fixed engines had many advocates; the locomotive very few: it stood as yet almost in a minority of one—George Stephenson....