Page:Popular Science Monthly Volume 21.djvu/163

Rh Newcomb's animadversions on my chapters on the kinetic theory of gases and transcendental geometry. On the former he expatiates as follows:

For the benefit of the non-scientific reader we may say that there is no theory of modern physics, the processes supposed by which are invisible to direct vision, which is more thoroughly established than this. It explains with the utmost simplicity and without introducing any but the best known properties of molecules, a great number of diverse phenomena, seemingly incapable of explanation in any other way. The only objection of the author which we can completely understand is that the theory in question—i. e., the kinetic theory of gases—seems to him incompatible with his own favorite doctrine that molecules are inelastic. Should he have any hesitation in pitting his a priori idea against so widely received a theory, it should relieve him to know that the supposed antagonism arises only from his own misapprehension. No elasticity is assigned the molecules in the kinetic theory, but only an insuperable, repulsive force which causes the molecules to repel each other when they are brought sufficiently near together. The reader who has any interest in following the author in his attempt to show that Maxwell and his co-laborers were guilty of a long series of fallacies and errors in attempting to prove the theory in question, may read the chapter, as an abstract is impossible.

So "no elasticity is assigned to the molecules in the kinetic theory." Well, that is startling news indeed! I hope it has been conveyed to Sir William Thomson, who at latest accounts was still engaged in the arduous, but, as we are now informed by Professor Newcomb, utterly useless study of vortex-rings, which he hopes to make available as substitutes for elastic atoms or ultimate molecules. At the last meeting of the British Association Sir William Thomson read a paper "On the Average Pressure due to the Impulse of Vortex-Rings on a Solid," of which an abstract is published in "Nature" for May 12, 1881 (vol. xxiv, pp. 47, 48). In this paper Sir William says:

The pressure exerted by a gas composed of vortex-atoms is exactly the same as is given by the ordinary kinetic theory, which regards the atoms as hard elastic particles.

I do not deem it necessary to multiply quotations from the writings of other scientific men in support of my statement that the kinetic theory of gases can not dispense with the assumption of the elasticity of ultimate-molecules. No intelligent reader who has glanced at page 42 of my book can be in any doubt as to what is taught on the subject by the founders and promoters of the theory in question. But I will add one citation, because it is from a book to which I shall have occasion to refer for another purpose. The most thorough mathematical treatise on the kinetic theory of gases, indorsed as such by Clerk Maxwell, is the well-known little book of Henry William Watson. It is in the form of propositions; and the very first words of the first proposition are these: