Ɛpsilon

To G. H. Darwin   22 October [1874]1

Down, | Beckenham, Kent.

Oct 22d.

My dear G.

I send index.— You need not look over the pages of Ch. XX. There will be no occasion for Revise & do not correct anything except actual errors— I send 2d. vol. of Descent for Printers have not sent old Proofs. If at all intelligible, it is useless to make any expression in Index better. Make any corrections very clear. Return proofs as soon as you can to Clowes address—ie “Stamford St. Blackfriars, London.”—2

Please return 2d. vol. of Descent by Post.—

And now can you answer me 2 queries in physics. I am nearly sure that some crystals & I think fibrous iron conduct heat more easily or quickly in certain directions than in others.— Is not this so?

Secondly, I believe a very hot body radiates heat quicker than a less hot body; but how is this in conduction. Is heat conducted away more quickly or easily from a very hot than from a less hot body? It is too long a story to explain why I want this information; it is to illustrate, as mere analogy, the transmission of the motor impulse through the leaves of Drosera.3

Yours affect | C. Darwin

1
The year is established by the relationship between this letter and the letter from G. H. Darwin, 24 October 1874.
2
George was assisting with the second edition of Descent, published in a single volume in November 1874 (letter from R. F. Cooke, 12 November 1874). William Clowes & Sons were the printers used by CD’s publisher, John Murray. From 1827, their printworks were in Duke Street (now Duchy Street), off Stamford Street, between Blackfriars and Waterloo Bridge in London (Clowes [1953], pp. 25–6).
3
In Insectivorous plants, pp. 234–43, CD discussed his experiments on the transmission of the motor impulse in Drosera rotundifolia (the round-leaved or common sundew).

Manuscript Alterations and Comments

1.2 actual] interl
1.4 in Index] interl
3.2 or quickly] interl

Please cite as “DCP-LETT-9693,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-9693