Little Masterpieces of Science - Invention and Discovery — Count Rumford Identifies Heat with Motion

[6] Some years ago I sent an outline of this argument to Herbert Spencer, who replied: "I recognize a novelty and value in your inference that the law implies an increasing width of gap between lower and higher types as evolution advances."

COUNT RUMFORD IDENTIFIES HEAT WITH MOTION.

[Benjamin Thompson, who received the title of Count Rumford from the Elector of Bavaria, was born in Woburn, Massachusetts, in 1753. When thirty-one years of age he settled in Munich, where he devoted his remarkable abilities to the public service.

Twelve years afterward he removed to England; in 1800 he founded the Royal Institution of London, since famous as the theatre of the labours of Davy, Faraday, Tyndall, and Dewar.

He bequeathed to Harvard University a fund to endow a professorship of the application of science to the art of living: he instituted a prize to be awarded by the American Academy of Sciences for the most important discoveries and improvements relating to heat and light.

In 1804 he married the widow of the illustrious chemist Lavoisier: he died in 1814. Count Rumford on January 25, 1798, read a paper before the Royal Society entitled "An Enquiry Concerning the Source of Heat Which Is Excited by Friction."

The experiments therein detailed proved that heat is identical with motion, as against the notion that heat is matter.

He thus laid the corner-stone of the modern theory that heat light, electricity, magnetism, chemical action, and all other forms of energy are in essence motion, are convertible into one another, and as motion are indestructible.

The following abstract of Count Rumford's paper is taken from "Heat as a Mode of Motion," by Professor John Tyndall, published by D. Appleton & Co. , New York.

This work and "The Correlation and Conservation of Forces," edited by Dr. E.

L.

Youmans, published by the same house, will serve as a capital introduction to the modern theory that energy is motion which, however varied in its forms, is changeless in its quantity.

] Being engaged in superintending the boring of cannon in the workshops of the military arsenal at Munich, Count Rumford was struck with the very considerable degree of heat which a brass gun acquires, in a short time, in being bored, and with the still more intense heat (much greater than that of boiling water) of the metallic chips separated from it by the borer, he proposed to himself the following questions: "Whence comes the heat actually produced in the mechanical operations above mentioned?

"Is it furnished by the metallic chips which are separated from the metal?"

If this were the case, then the _capacity for heat_ of the parts of the metal so reduced to chips ought not only to be changed, but the change undergone by them should be sufficiently great to account for _all_ the heat produced.

No such change, however, had taken place, for the chips were found to have the same capacity as slices of the same metal cut by a fine saw, where heating was avoided.

Hence, it is evident, that the heat produced could not possibly have been furnished at the expense of the latent heat of the metallic 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° 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°.

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° 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 apparatus was set in action.

The temperature of the water on commencing was 60°.

"The result of this beautiful experiment," writes Rumford, "was very striking, and the pleasure it afforded me amply repaid me for all the trouble I had had in contriving and arranging the complicated machinery used in making it.

The cylinder had been in motion but a short time, when I perceived, by putting my hand into the water, and touching the outside of the cylinder, that heat was generated.

"At the end of one hour the fluid, which weighed 18. 77 pounds, or two and one-half gallons, had its temperature raised forty-seven degrees, being now 107°.

"In thirty minutes more, or one hour and thirty minutes after the machinery had been set in motion, the heat of the water was 142°.

"At the end of two hours from the beginning, the temperature was 178°.

"At two hours and twenty minutes it was 200°, and at two hours and thirty minutes it _actually boiled_!"

"It would be difficult to describe the surprise and astonishment expressed in the countenances of the bystanders on seeing so large a quantity of water heated, and actually made to boil, without any fire.

Though, there was nothing that could be considered very surprising in this matter, yet I acknowledge fairly that it afforded me a degree of childish pleasure which, were I ambitious of the reputation of a grave philosopher, I ought most certainly rather to hide than to discover."

He then carefully estimates the quantity of heat possessed by each portion of his apparatus at the conclusion of the experiment, and, adding all together, finds a total sufficient to raise 26. 58 pounds of ice-cold water to its boiling point, or through 180° Fahrenheit.

By careful calculation, he finds this heat equal to that given out by the combustion of 2,303. 8 grains (equal to four and eight-tenths ounces troy) of wax.

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.