Scientific American Supplement No. 819, September 12, 1891 eBook

This eBook from the Gutenberg Project consists of approximately 111 pages of information about Scientific American Supplement No. 819, September 12, 1891.
a congeries of discrete bodies, even if these bodies were the ultimate molecules of matter.  The planets might have been formed by the gradual accretion of such discrete bodies.  On the view that the material of the condensing solar system consisted of separate particles or masses, we had no longer the fluid pressure which was an essential part of Laplace’s theory.  Faye, in his theory of evolution from meteorites, had to throw over his fundamental idea of the nebular hypothesis, and formulated instead a different succession of events of which the outer planets were formed last, a theory which had difficulties of its own.  Professor George Darwin had recently shown, from an investigation of the mechanical conditions of a swarm of meteorites, that on certain assumptions a meteoric swarm might behave as a coarse gas, and in this way bring back the fluid pressure exercised by one part of the system on the other, which was required by Laplace’s theory.  One chief assumption consisted in supposing that such inelastic bodies as meteoric stones might attain the effective elasticity of a high order which was necessary to the theory through the sudden volatilization of a part of their mass at an encounter, by which what was virtually a violent explosive was introduced between the two colliding stones.  Professor Darwin was careful to point out that it must necessarily be obscure as to how a small mass of solid matter could take up a very large amount of energy in a small fraction of a second.

HELMHOLTZ’S DISCOVERY.

The old view of the original matter of the nebulae, that it consisted of a “fiery mist,”

            “a tumultuous cloud,
      Instinct with fire and niter,”

fell at once with the rise of the science of thermodynamics.  In 1854, Helmholtz showed that the supposition of an original fiery condition of the nebulous stuff was unnecessary, since in the mutual gravitation of widely separated matter we had a store of potential energy sufficient to generate the high temperature of the sun and stars.  We could scarcely go wrong in attributing the light of the nebulae to the conversion of the gravitational energy of shrinkage into molecular motion.  The inquisitiveness of the human mind did not allow us to remain content with the interpretation of the present state of the cosmical masses, but suggested the question—­

                     What see’st thou else
      In the dark backward and abysm of time?

What was the original state of things?  How had it come about that by the side of ageing worlds we had nebulae in a relatively younger stage?  Had any of them received their birth from dark suns, which had collided into new life, and so belonged to a second or later generation of the heavenly bodies?

LOOKING BACKWARD.

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Scientific American Supplement No. 819, September 12, 1891 from Project Gutenberg. Public domain.
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