WCP2778

[1]

Harlton

Cambridge

5 Oct[ober] 1899

My dear Sir.

Mr Chamberlin¹ sent me a copy of his paper. It had been so universally considered that the earth was once wholly melted that I think it would be necessary to adduce strong reasons against this to convince one. I think Chamberlin's argument has much force that, if the earth was built up of meteorite, it is more probable that they should have come in gradually than all at once — or very rapidly. It is only in the latter case that fusion would have followed. But it has always seemed to me that the meteorites are as difficult to account for as the earth itself ^considered as a portion of [2] the original solar nebula. We do not know where meteorites are formed now, or whether they are fragments of larger bodies or not.

But on reading Chamberlin's paper it struck me that th his theory could not explain the increase of density towards the centre of the earth. Unless the material was liquid, I do not see how the denser particles could have gravitated downwards. The increased pressure at great depths would not I think be any help; for the pressure upon a square inch (say) of a light mass would be the same as upon a square mile of a heavy one. The weight of a body within the earth diminishes as the centre is approached. Of course the ratio of the of the weight of two bodies would be the same as at the surface, ^{and proportional to their gravities} but their inertia would not be affected by the depth, so that the denser body would not be so easily moved as the less denser [3]³ If you piled up a mixed ^mixture of stones and buckets in a tall vessel the buckets would never get to the bottom.

As to oceanic basins I still think my theory in Ch[apter]. xxv[?] worthy of consideration². Depend upon it the moon has had more to do with the earth's history than has been accorded to her. It is the old story cherzchez[?] cherchez la femme.

Touching the world's age, I expect a short letter of mine appears in "Nature" today.

On this subject I have received an interesting and ingenious ^chemical paper by Prof[essor]. Joly³. I see objections to his theory, & have written to my friend Prof[essor] [word illeg.] about it. But I have not yet had an answer. I have asked him to help me in making a weighing in his laboratory. I do not expect him to give me an[?] opinion on Greig's[?] theory. Experts are shy of doing that.

I am very pleased to have heard from you again.

Believe me | Sincerely yours | Osmond Fisher⁴[signature]

Dr Wallace

P.T.O. [4]

Huxley's analogy of the mill and the peascod^5,6 has been quoted ad nauseum but it is a good one. In mathematical investigations one must examine the peascods & take the flour for granted. In Kelvin's⁷ estimate of the world's age the peascods are solidity.