And here it must be remembered that the matter which composes our earth and the other planets and the comets was probably all cast out from the same source, the sun, and hence a uniformity runs through it all. Humboldt says:
"We are 'astonished at being able to touch, weigh, and chemically decompose metallic and earthy masses which belong to the outer world, to celestial space'; to find in them the minerals of our native earth, making it probable, as the great Newton conjectured, that the materials which belong to one group of cosmical bodies are for the most part the same."[1]
[1. "Cosmos," vol. iv, p. 206.]
{p. 254}
Some aërolites are composed of finely granular tissue of olivine, augite, and labradorite blended together (as the meteoric stone found at Duvets, in the department de l'Ardèche, France):
"These bodies contain, for instance, crystalline substances, perfectly similar to those of our earth's crust; and in the Siberian mass of meteoric iron, investigated by Pallas, the olivine only differs from common olivine by the absence of nickel, which is replaced by oxide of tin."
Neither is it true that all meteoric stones are of iron. Humboldt refers to the aërolites of Siena, "in which the iron scarcely amounts to two per cent, or the earthy aërolite of Alais, (in the department du Gard, France,) which broke up in the water," (clay?); "or, lastly, those from Jonzac and Juvenas, which contained no metallic iron."[2]
Who shall say what chemical changes may take place in remnants of the comet floating for thousands of years through space, and now falling to our earth? And who shall say that the material of all comets assumes the same form?
I can not but continue to think, however, until thorough scientific investigation disproves the theory, that the cosmical granite-dust which, mixed with water, became clay, and which covers so large a part of the world, we might say one half the earth-surface of the planet, and possibly also the gravel and striated stones, fell to the earth from the comet.
It is a startling and tremendous conception, but we are dealing with startling and tremendous facts. Even though we dismiss the theory as impossible, we still find ourselves face to face with the question, Where, then, did these continental masses of matter come from?