An Expository Outline of the Vestiges of the Natural History of Creation | Page 4

whose distances have been calculated, and to express them, miles, leagues, or orbits seems inadequate. Light, whose speed is known to be 192,000 miles per second, would be three years in reaching our earth from the star of HENDERSON; and starting from BESSEL'S star and moving at the same rate it could only reach us in ten years. These are the nearest stars, but there are others whose distances are immeasurably greater, and whose light, though starting from them at the beginning of creation, may not have reached our globe!
The stars visible to the eye are about 3,000, but the number increases with every increase of telescopic power, and may be said to be innumerable. They are not of uniform lustre or form, but vary in figure and brightness. Some of them have a nebulous or cloudy appearance; and there are entire clusters with this dusky aspect, mostly pervaded, however, with luminous points of more brilliant hue. In the outer fields of astral space Sir WILLIAM HERSCHEL observed a multitude of nebul?, one or two of which may be seen by the naked eye. All of them, when seen by instruments of low power, look like masses of luminous vapour; but some of them had brighter spots, suggesting to Sir WILLIAM the idea of a condensation of the nebulous matter round one or more centres. But when these luminous masses are examined by more powerful instruments many of them lose their cloudy form, and are resolved into shining points, "like spangles of diamond dust." It is in this way several nebul? have yielded to the gigantic reflector of Lord ROSSE, and others with still greater optical resources may follow. This brings us to the first questionable and controversial portion of the Vestiges; namely,--the
NEBULAR HYPOTHESIS.
It is among the gaseous bodies just described, in the outer boundary of Nature, which neither telescope nor geometry can well reach, that speculation has laid its venue, and commenced its aerial castles. LAPLACE was the first to suggest the nebular hypothesis, which he did with great diffidence, not as a theory proved, or hardly likely, but as a mathematical possibility or illustration. His range of creation, moreover, was not so vast as that of our author, which assumes to compass the entire universe, but was limited to the evolution of the solar system. The mode in which this might be evolved, LAPLACE thus explains:--
He conjectures that in the original condition of the solar system the sun revolved upon his axis, surrounded by an atmosphere which, in virtue of an excessive heat, extended far beyond the orbits of all the planets, the planets as yet having no existence. The heat gradually diminished, and as the solar atmosphere contracted by cooling, the rapidity of its rotation increased by the laws of rotatory motion, and an exterior zone of vapour was detached from the rest, the central attraction being no longer able to overcome the increased centrifugal force. The zone of vapour might in some cases retain its form, as we still see in Saturn's ring; but more usually the ring of vapour would break into several masses, and these would generally coalesce into one mass, which would revolve about the sun. Such portions of the solar atmosphere abandoned successively at different distances, would form planets in the state of vapour. These masses of vapour, it appears from mechanical laws, would have each its rotatory motion, and as the cooling of the vapour still went on, would each produce a planet that might have satellites and rings formed from the planet, in the same manner as the planets were formed from the atmosphere of the sun.
All the known motions of the solar system are consistent and reconcileable with this theory of LAPLACE, and upon it the author of the Vestiges has enlarged and founded his wider scheme of physical creation. He supposes the void of nature to have been originally filled with a universal FIRE MIST (p. 30), out of which all the celestial orbs were made and put in motion. How this mist was put in activity, and resolved into the luminous and revolving bodies that we now see, and one of which we inhabit is the first urgent perplexity to surmount in the conjecture. It is manifest that if a mist filled the entire region of space, a mist it must for ever remain, unless acted upon by some cause adequate to give it new action and arrangement. No sun, no stars or planets could spontaneously emanate from an inert vapour any more than from nothing. To meet this, his first difficulty, the author supposes that there were certain nuclei, or centres of greater condensation, analogous to those still remarked in the nebul? of the heavens, and that these nuclei, by their superior attractive force, consolidated into