1. Of all the theories touching the origin of being, that which has received the most credit in recent days is that of Buffon, perhaps by reason of the place its author held in the scientific world, perhaps because knowledge on the subject was slender at the time.
By seeing all the planets moving in the same direction and in the same plane from the occident to the orient, from west to east, going over orbits of which the inclination does not exceed seven and a half degrees, Buffon concluded, by this uniformity, that they must all move in obedience to the same cause.
According to him, the sun being an incandescent melted mass, he supposed that a comet, having been hurled obliquely against it, by knocking against its surface, had detached a portion, which, projected into space by the violence of the shock, became divided into many fragments. These fragments have formed planets, which have continued to move circularly, by the combination of centripetal and centrifugal force, in the way communicated by the direction of the original shock; i.e., in the plane of the ecliptic.
Planets must then be parts of the incandescent substance of the sun, and consequently incandescent themselves at their commencement. They have been submitted to a cooling and consolidating process during a period of time proportionate to their volume; and, when the temperature has permitted, life has appeared on their surface.
In consequence of the gradual lowering of the central heat, the Earth would arise in a given time to a completely cool state; the liquid mass would be entirely frozen; and the air, more and more condensed, would finally disappear. The lowering of the temperature, rendering life impossible, would lead to the diminution, then to the disappearance, of all organized beings. The cooling process which has commenced at the poles would pass successively from one country to another until it reached the equator.
Such is, according to Buffon, the present state of the moon, which, smaller than the Earth, should be now an extinguished world, whence life is henceforth excluded. The sun itself will some day end in the same manner. According to his calculation, it must have taken the Earth about seventy-four thousand years to arrive at its present temperature, and in ninety-three thousand years it must see the end of organized nature.
2. The Theory of Buffon - Contradicted by more recent discoveries in science, is now almost entirely abandoned for the following reasons:
1 - For a long time it was believed that comets were solid bodies, which, coming in collision with planets, would destroy them. According to this hypothesis the supposition of Buffon was not improbable; but is now known that they are formed of a gaseous, condensed substance, rarefied enough, however, to allow of stars of less magnitude being visible through their nucleus. In this state, offering less resistance than the sun, a violent shock capable of projecting afar a portion of its substance is an impossible thing.
2 - The incandescent nature of the sun is equally a hypothesis, as nothing yet discovered confirms it. The results of observation all point, however, in an opposite direction. Although its nature as yet has not been quite determined upon, the means of observation are very much improved, and thus it can be much better studied. It is now generally admitted by scientists that the sun is a globe composed of a solid substance, surrounded by a luminous atmosphere, which is not in contact with its surface. *
3 - In the times of Buffon the six planets familiar to the ancients were the only ones discovered, - Mercury, Venus, Earth, Mars, Jupiter, and Saturn. Since then there have been discovered a number, of which the three principal – Juno, Ceres, and Pallas – have an inclined orbit of thirteen, ten, and thirty-four degrees respectively, which does not accord with the movement of unique projection.
4 - The calculations of Buffon upon the cooling process have been recognized as completely wrong since the discovery of the law of the diminution of heat by M. Fourier. Therefore, not only seventy-four thousand years have been necessary to develop the present temperature of the Earth, but rather millions of years.
5 - Buffon has considered only the central heat of the globe, without taking into account that of the sun’s rays. Now it is recognized by scientific facts, rigorously founded upon experience that, by reason of the thickness of the terrestrial crust, the internal heat of the globe has for a long time played only an insignificant part in regulating the temperature of the surface. The variations to which the atmosphere is submitted are periodical and due to the preponderating action of the solar heat (see chap. VII, n° 25). The effect of this cause being permanent, whilst that of the central heat is hardly anything, the diminution of the latter can bring to the surface of the Earth no sensible modification in order that the Earth should become uninhabitable by the general cooling process: the extinction of the sun would be necessary. **
* One will find a complete dissertation, according to modern science, upon the nature of the sun and comets in “Studies and Lectures upon Astronomy,” by Camille Flammarion.
** For details on this subject, and for the law of the diminution of heat, see “Letters upon the Revolution of the Globe” by Bertrand pages 19 and 307. This work, which was written with simplicity and without a spirit of system, offers, in terms of modern science, a geological study of great interest.