To T. H. Farrer   20 October 1880

My dear Farrer

What a man you are to do thoroughily whatever you undertake to do! The supply of specimens has been magnificent, & I have worked at them for a day & a half.¹ I found a very few well rounded grains of brick in the castings from over gravel walk, & plenty over the hole in field & over Roman floor. You have done me the greatest possible service by making me more cautious than I sh^d. otherwise have been, viz by sending me the rubbish from the road itself; in this rubbish I find very many particles, rounded (I suppose) by having been crushed, angles knocked off, & somewhat rolled about. But not a few of the particles may have passed through the bodies of worms during the years since the road was laid down.— I still think that the fragments are ground in the gizzards of worms, which always contain bits of stone; but I must try & get more evidence. I have today started a pot with worms in very fine soil, with sharp fragments of hard tiles laid on the surface, & hope to see in the course of time whether any of these become rounded.² I do not think that more specimens from Abinger would aid me.

With hearty thanks for all your most kind assistance, I am | My dear Farrer | Yours sincerely | Charles Darwin

Eliz. Wedgwoods progress is, I fear, decidedly downwards, but she had a rather better night.—³ She suffers greatly from extreme restlessness & short-breathing. Her life, I think, is a misery to her.