No. 9.

On the Origin of Comets and Meteors.

The extreme velocity of many comets and meteors is such that it is impossible the motion could have been developed by our own solar system. These bodies are consequently outside visitants passing through our system in hyperbolic orbits, and at other times travelling independently through space, swayed by this or that star, but owing allegiance to no cosmical page 10 body. In some bodies the velocity is so great, as for instance in the star 1830 Groom bridge, that probably they are even independent of the visible universe. It is also probable from the inclination of their planes, from the great eccentricity of their orbits, and the various direction of their motions, that all, even the periodic comets and meteors, may have originally been visitants to the solar system, with but a small original independent velocity, which has been destroyed either by the retarding influence of a planet approaching their path, or by the retarding action of the cosmical matter, the existance of which the zodiacal light and corona render probable. As it has been shewn that meteoric bodies and comets must be numbered by millions; some process by which bodies, with independent velocities, may be produced, must be at work in space. I shall attempt to shew that partial impact may certainly have an action in this direction, There are several ways in which this hypothesis shews these bodies may have been produced. I shall in this letter only describe one. I have already explained that in the partial impact of two bodies, generally three masses will be produced. The parts of each that are in each other's line of motion would coalesce and form one body, which I have shewn possesses many peculiar kinematic and kinetic properties, both molar and molecular, It also possesses enormous energy proportional to its mass, and will in most cases throw off many pieces, and sometimes, when of a very small ratio compared to the original masses they will dissipate entirely into space. In this particular discussion it will not be necessary to speak of the two independent bodies, as it is certain their motion will be finally smaller than it was originally. But with the central body it is quite different; some parts of this body may have a velocity many times as fast as its own attractive force could give them. These parts may clearly become independent wanderers. Nor will the retreating masses exercise any great attraction on the central mass, as each of them will be pulling it in opposite directions. Under any circumstances their attraction will be exercised at great disadvantages as regards direction and distance, and will be partially opposite, under any circumstances. In fact a careful inspection of the case will shew physicists that the retreating bodies may in many eases be tending to increase the final velocity of the escaping pieces of the central mass, during all the time that this attraction is sufficiently powerful to have any appreciable effect, I have discussed some of the molecular possibilities of these masses in a paper read before the Philosophical Institute of Canterbury. I shall in future letters have to discuss others, but it will readily be seen that these bodies may be either solid, liquid, or gaseous, dependent on the constitution, the velocity, and the original temperatures of the two attracting masses. It is clear that in any small mass of the coalesced body they want of balance of the momentumof its several parts will be nearly a constant quantity, and it will consequently tend to give a parallel direction to those escaping fragments, which would be aided by their own attraction in space. This may be one cause for the meteoric trains. I have thus shewn, I hope, with sufficient clearness, the general idea of one of the many explanations partial impact appears to furnish for the development of high independent velocities in small bodies.