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Updated: June 16, 2025
Although this ring theory of the formation of the planets and satellites is not completely proved, the occurrence of such a structure as that which girdles Saturn affords presumptive evidence that it is true. Taken in connection with what we know of the nebulæ, the proof of Laplace's nebular hypothesis may fairly be regarded as complete.
Swiftly now I move across the border into manhood a serious, eager, restless manhood. It was the fashion of the young those days. I spent a summer of hard work in the fields. Evenings I read the books which Mr. Wright had loaned to me, Blackstone's Commentaries and Greenleaf on Evidence and a translation by Doctor Bowditch of LaPlace's Mécanique Celeste. The latter I read aloud.
The nebular hypothesis, Laplace's or Compte's theory of planets shelled off from the sun, spontaneous generation, some of these vagaries, we admit, are of much older date than the year 1800, the Macleay system, dogs playing dominoes, negroes born of white parents, materialism, phrenology, he adopts them all, and makes them play an important part in his own magnificent theory, to the exclusion, in a great degree, of the well-accredited facts and established doctrines of science.
And as having the same meanings let me not omit the remarkable fact concerning the planetoids discovered by D'Arrest, that "if their orbits are figured under the form of material rings, these rings will be found so entangled, that it would be possible, by means of one among them taken at hazard, to lift up all the rest," a fact incongruous with Laplace's hypothesis, which implies an approximate concentricity, but quite congruous with the hypothesis of an exploded planet.
For more than three-quarters of a century Laplace's celebrated hypothesis of the manner of origin of the solar system from a rotating and contracting nebula surrounding the sun had guided speculation on that subject, and had been tentatively extended to cover the evolution of systems in general.
She had already devoted much attention, especially during her widowhood, to mathematics and astronomy; and after her second marriage she had no difficulty in pursuing these studies. She adapted Laplace's Mécanique Céleste in 1823, and followed it up by more original work on physics, astronomy, and physical geography.
If they are truly elliptical they accord fairly well with Laplace's idea, except that the scale of magnitude is stupendous, and if the Andromeda Nebula is to become a solar system it will surpass ours in grandeur beyond all possibility of comparison.
A glance at the extraordinary variations upon the spiral which Professor Keeler's photographs reveal is sufficient to convince one of the difficulty of the task of basing a general theory upon them. In truth, it is much easier to criticize Laplace's hypothesis than to invent a satisfactory substitute for it.
The resolution of the so-called ansæ, or "handles," into one encircling ring by Huygens in 1655, the discovery by Cassini in 1675 of the division of that ring into two concentric ones, together with Laplace's investigation of the conditions of stability of such a formation, constituted, with some minor observations, the sum of the knowledge obtained, up to the middle of the last century, on the subject of this remarkable formation.
And, in 1811, M. Poisson applied Laplace's artifices to the case of two spheres acting upon one another in contact, a case to which many of Coulomb's experiments were referrible; and the agreement of the results of theory and observation, thus extricated from Coulomb's numbers obtained above forty years previously, was very striking and convincing."
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