With respect to meteorites the same author remarks that "like the moon, they are probably satellites of the earth; but being very small, they are liable to extraordinary perturbations, and hence strike the earth in many directions." Here, again, his _facts_ are at fault; for (1) the observed velocities of these bodies are inconsistent with the supposition of their being satellites of the earth; and (2) the amount of perturbation of such bodies does not vary with their masses: a _small_ meteorite would fall toward the earth or any other planet with no greater velocity than a _large_ one. THE METEORIC THEORY. It has been shown in a previous chapter that immense numbers of meteoric asteroids are constantly traversing the planetary spaces--that many millions, in fact, daily enter the earth's atmosphere. Reasons are not wanting for supposing the numbers of these bodies to increase with great rapidity as we approach the center of the system. Moreover, on account of the greater force of gravity at the sun's surface the heat produced by their fall must be much greater than at the surface of the earth. It has been calculated that if one of these asteroids be arrested in perihelion by the solar atmosphere, the quantity of heat thus developed will be 9000 times greater than that produced by the combustion of an equal mass of coal. There can, therefore, be no reasonable doubt that a _portion_ of the sun's heat is produced by the impact of meteoric matter. In considering the probability that it is _chiefly_ so generated, the following questions naturally present themselves: 1. _What amount of matter precipitated upon the sun would develop the quantity of heat actually emitted?_--This question has been satisfactorily discussed by eminent physicists, and it will be sufficient for our purpose to give the result. According to Professor William Thomson, of Glasgow, the present rate of emission would be kept up by a meteoric deposit which would form an annual stratum 60 feet in thickness over the sun's surface. 2. _Could such an increase of the sun's magnitude be detected by micrometrical measurement?_--This inquiry is readily answered in the negative. The apparent diameter would be augmented only one second in 17,600 years. 3. _Is there any known or visible source from which this amount of meteoric matter may be supplied?_--Thomson, Mayer, and other distinguished writers regard the zodiacal light as the source of such meteorites. The inner portions of this immense "tornado" must be resisted in their motions by the solar atmosphere, and hence precipitated upon the sun's surface.