Dr. J. R. Mayer on the Mechanical Equivalent dfHeaK 511 



decision was come to long ago. But whether it is expedient to 

 call this magnitude a force is quite another question. 



Since, whenever an innovation of essential importance is pro- 

 posed, the public is so ready to misapprehend, I will here state 

 once more, as clearly as I can, my reasons for saying that " the 

 force of gravity " is an improper expression. 



It is an unassailable truth that the production of every falling 

 motion is connected with a corresponding expenditure of a mea- 

 surable magnitude. This magnitude, if it is to be made an 

 object of scientific investigation (and why should it not ?), must 

 have a name given to it; and in accordance with the logical 

 instinct of man, as manifested in the genius of language, no 

 other name can be here chosen than the word "force." But 

 since this expression is already used in a quite different sense, 

 we might be tempted to create for the conception which is as yet 

 — in the fundamental parts of science at least — unnamed an 

 entirely new name. But before betaking ourselves to this extreme 

 course, which for reasons that are not far to seek would be the 

 one whereby we should be brought most into conflict with exist- 

 ing usage, it is reasonable to inquire whether the word " force/' 

 which in itself answers so well to the requirements of the case, 

 is in its right place where it was first put by the schools. 



According to the common custom of speech, we understand 

 by " force " something moving — a cause of motion ; and if, on 

 the one hand, the expression " moving force " is for this reason, 

 strictly speaking, a pleonasm, the notion of a not moving or 

 " dead " force is, on the other hand, a contradictio in adjecto. 

 If it be said, for instance, that a load which presses with its 

 weight on the ground exerts thereby a force — a force which, 

 though never so great, is unable of itself to bring about the 

 smallest movement — the mode of conception and of expression 

 is quite justified by scholastic usage, but it is so far-fetched that 

 it becomes the source of unnumbered misapprehensions. 



Between gravity and the force of gravity there is, so far as I 

 Know, no difference ; and hence I consider the second expression 

 unscientific, inasmuch as it is tautological. 



Let it not be objected that the "force" of pressure, the "force" 

 of gravity, cohesive "force," &c. are the higher causes of pres- 

 sure, gravity, and the like. The exact sciences are concerned 

 with phenomena and measurable quantities. The first cause of 

 things is Deity — a Being ever inscrutable by the intellect of 

 man ; while " higher causes," " supersensuous forces," and the 

 rest, with all their consequences, belong to the delusive middle 

 region of naturalistic philosophy and mysticism. 



By a law that is universally true, waste and want go hand in 

 hand. If to the case before us, where this rule likewise meets 



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