Page:Popular Science Monthly Volume 58.djvu/477

Rh the animal, and accepting Rumford's statement that the work was that which could be readily performed 'by a single horse' the writer showed that the quantity of heat developed in Rumford's experiments, compared with the accepted datum, 25,920 foot-pounds per minute as the power of the horse, as given by Rankine, for the average case, or better, say 25,000 for the average Bavarian horse of the last century, we obtain as the 'mechanical equivalent' 783.8 foot-pounds, differing from 778, the accepted figure of Rowland and later authorities, by but six units, less than 1 per cent, of its own value and vastly nearer than any figures obtained up to our own time.

Thus, as the writer claimed in 1873, we may state the achievement of that great philosopher and engineer in the following terms:

 1. Rumford was the first to prove experimentally the immateriality of heat. 2. He was the first to indicate and directly to prove it to be a form of energy; publishing his proof a year before Davy. 3. Rumford first, a half-century before Joule, determined by experimental research the quantivalence of thermal and dynamic energies, and secured data giving the value of the factor of equivalence with almost perfect accuracy. 4. He is entitled to the sole credit of the experimental discovery of the true nature of heat, of its equivalence with mechanical energy and its measure of quantivalence.

The work of Sir Humphry Davy was of great importance; but it was in confirmation of the deductions previously announced to the Royal Society by his contemporary and colleague, Rumford.

"Benjamin Thompson, of Concord, New Hampshire, commonly known as Count Rumford, the Bavarian, should be accorded a higher position and a nobler distinction than has yet been given him by writers on thermodynamics."

Rumford, above all others, ancient or modern, is entitled to the credit of not only laying down an experimental foundation for the 'Law of Substance' and the principle of persistence of energy, but also for actually making it a physical, rather than as previously a metaphysical, topic; for proving the falsity of the older views of the nature and origin of heat in thermodynamic systems, for proving by direct test and experimental investigation the immateriality of heat and its real character as a 'mode of motion' as Tyndall called it, as a form of energy more properly. He furnished a method and means of estimating the 'mechanical equivalent of heat'; he originated by actual work of research a true statement of the principle of the quantivalence of the two forms of