admitted, yet that the cosmical forces available at the time of the consolidation of the earth would have been sufficient for the purpose. It must also be remembered that we have no reason to believe there is any substantial difference between the materials in the sun and the materials of which the earth is composed. The gases by which explosions in the sun generate velocities of many hundreds of miles a second, are only the same gases as those which are found on the earth. It therefore appears that by the study of solar phenomena the objection to the terrestrial theory of meteorites on account of the great initial velocity required may be said to have been considerably abated, if not entirely overcome.
There is another objection which has been frequently urged against the hypothesis of the terrestrial origin of meteorites. We have been reminded of the existence of the earth's atmosphere, and attention has been called to the fact that a missile discharged from the lower strata of that atmosphere with an enormous speed would find its velocity greatly reduced by the resistance of the medium through which it had to cleave its way. It has thus been maintained that when the body reached the outer layers of the atmosphere it could not have retained sufficient speed to carry it away from the earth. I freely admit that this is a difficulty. Artillerists know well that the resistance of the air robs their projectiles of energy and greatly reduces the range and the effectiveness of their weapons. Nor am I surprised that this difficulty may have sometimes appeared to be a very formidable one when urged against the doctrine of the terrestrial origin of meteorites. There are, however, certain considerations which will, I think, show that the objections founded on
