WCP6890

[1]

Parkstone, Dorset.

March 29th, 1901

My dear Mr Fisher

I have read your paper with great interest and am glad to find you do not consider it supplies very strong arguments against the meteoric theory. There are only one or two points on which I have any remark to make period.

1. Your argument as to the difference between composition of meteorites and of our rocks seems of little weight, because the elements in meteorites as so few; and all the rocks we can get at have been subject for millions of years to varying heat, & chemical reactions, &, most important of all, have been ground down by air & water and sorted & sifted again & again, & again compressed and heated & worked all over again & again, How can there be any resemblance? [2]

2. Gases form a very important part of the earth's crust, especially oxygen, nitrogen, & hydrogen. These, in space, would all be liquids or solids, and on the meteoritic theory must occasionally have come ⁱⁿ with other matter, to form the earth.

Perhaps aqueous-vapour may have come in as snow, hail or ice balls, & carbon dioxide in the solid state. Then, all these w^d help to fill up the interstices between the rocky meteorites proper ^{or meteoric dust} and as the aggregation went on, & heat was produced, these would be subject to expansion,— would then form compounds and in doing so give out more heat.

In the cold of interplanetary space we must look on all the gases as solid or liquids, and in large quantities they would act as ice [3] does — that is, require a good deal of time to return to the gaseous state even under considerable heat.

Again, the aggregation of matter might have been intermittent, and any of those gases that escaped to the surface would be first liquefied then solidified ^{by the cold}, & then perhaps buried under a rapid downfall of fresh matter.

Some such conditions as these must have occurred on the meteoritic theory; and I do not think you consider them sufficiently.

Again, without dealing with anything beyond the earth-formation, I think you should give a statement of this objection to the nebular theory. A nebulous ring is left behind by the contracting sun, which gradually cools, comes together & forms the earth. But this nebulous ring [3] in space was primarily somewhat irregular though universally diffused. It is not difficult to conceive how all the subsequent changes and groupings, nebulae and stars and systems, came into existence.

The conclusion would be, that the solar-system never was a gaseous mass extending to the farthest planet, but rather a huge ^irregular meteoritic swarm, gradually contracting, rotating, and heating under the action of gravity, the more condensed outer portions of it forming separate agglomerations which became [4] planets. if this is correct, it will follow that Geo. Darwin's theory of the origin of the Moon is not necessarily correct, and the whole calculation of age and of tidal deformation &c. deduced from that theory may have no real foundation. The earth & all the planets may have been formed by an agglomeration or solid particles towards one of the many denser portions of the contracting meteor swarm, and the moon ^may have originated by a sub-ordinate centre of attraction. In that case I presume there would be no real tidal action, the separate [5]¹ must have been indefinitely less dense than the highest vacuum in one of Crookes' tubes! Yet it comprised all the elements in the earth in a state of gas, implying heat many times hotter than the electric arc! During the process of cooling (in space at zero temp.) all the most refractory elements — iron silica, aluminium &c. would solidify & fall in first, & should all be at the earth's centre, and none outside.

But the whole conception is to me impossible!

Yours very truly | Alfred R. Wallace [signature]