Elasticity Explained.
Elasticity of solids is explained on the same principle. If we swiftly turn a gyroscopic wheel we can only change its plane of rotation by an effort, which effort is repaid when the metal is allowed to resume its original plane of motion. It is imagined that in like manner the particles in an elastic spring move rapidly in a definite plane; if deflected therefrom they oppose resistance and are ready to do work in returning thereto. Of kindred to the kinetic theory of elasticity is the explanation of heat as a distinct and ceaseless molecular motion on which the dimensions of masses depend. It has long seemed to me that every case of “potential” energy, as that of a spring bent or coiled, may in like manner embody actual though impalpable and invisible motion. I presented this view in the Popular Science Monthly, December, 1876.
The very constitution of matter is now referred to the motions, highly diversified, of the simplest substance possible. Helmholtz, Lord Kelvin, and Professor Clerk Maxwell have imagined the molecules of lead, iron, or other element as vortices born of the ether in which without resistance they forever whirl. As we see in the case of a quickly rotated chain, substantial rigidity is conferred by motion sufficiently swift. Nor are molecules without somewhat of individuality. We are wont to think of masses of solid iron as precisely similar in quality, but experience shows us that one bar of iron may vary from another by all that has differenced the history of the two. A careful workman uses a steel die for only a short service before he returns it to the annealer, well assured that the metal, despite its seeming wholeness, has suffered severe internal strain at every blow, which, were no caution exercised, would soon reveal itself in fracture of the die, or ruined work. Facts of this kind, which every day confront the mechanic and engineer, convey a prophecy of the sensibility and memory which dawn with life.