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Darwin Correspondence Project

To G. H. Darwin   [9 December 1868]1


Wednesday night—

My dear George

Many thanks for your note. I am heartily glad that dear old Backy is going on so well.2 It gives me an awesome shudder whenever I think of it, & that is a deal too often. Tell him with my love to be sure to obey strictly the surgeon’s directions; for I remember Engleheart said when Mrs. Evans cut quite a small artery, that there was liability for longish time for the cut to open.—3 I am glad to hear that he is able to dissect. Tell him that I quoted with wonderful success the other day at the Nortons his proverb that “a fib in time saves nine”.4

I suppose you will not bring home Thompson’s big Book; so will you look & see exactly what he says (if he says anything) how many millions of years ago the crust of the Earth first became solidified so that it cd. have supported living beings.5 Croll quotes a passage rather too briefly for me.6

See if Thompson refers to any other papers by himself on subject.— I wish I knew what Haughton had said.—7 It is partly for this that I want Lyell’s Principles, & you had better bring Lyell’s other book.—8 Croll has most kindly sent me excellent M.S. abstract of his views & a volume with all his own papers, which I must return, but have kept for you to read; however, I fear you will not have time on account of Wales.9 The brevity of the world troubles me, on account of the pre-silurian creatures which must have lived in numbers during endless ages, else my views wd be wrong, which is impossible — Q.E.D.—10

I have got Owen’s book, but had not noticed the pile of abuse against me & which I must soon read. I shd have never twigged the D.T.—11 I daresay I shall want much advice about Croll & Thompson & be hanged to them.—

Your most affectly | C. Darwin

It is all for new Edit. of Origin.—12


The date is established by the relationship between this letter and the letter from G. H. Darwin, 8 December 1868. In 1868, the first Wednesday following 8 December was 9 December.
‘Backy’ was a childhood nickname for Francis Darwin (Darwin pedigree, p. 61). See letter from G. H. Darwin, 8 December 1868.
A note in pencil in George’s hand above the words ‘whenever I think of it’ reads ‘bad cut in thigh’. CD refers to Stephen Paul Engelheart and possibly to Margaret Evans.
Charles Eliot Norton and Susan Ridley Norton stayed for four months at Keston Rectory near Down (see letter to J. D. Hooker, [8–10 September 1868]). According to Emma Darwin’s diary (DAR 242), the Darwins saw the Nortons several times from September 1868 onwards, but no mention is made of a visit in December 1868. A note in pencil following the proverb reads ‘(mine really GHD)’.
CD refers to the Treatise on natural philosophy (W. Thomson and Tait 1867). In an appendix on secular cooling of the earth (W. Thomson and Tait 1867, pp. 711–27), William Thomson summarised and developed his earlier work on the topic; he estimated that the climate could not have been affected by the internal heat of the earth any later than 10,000 years after the formation of the earth’s crust (see p. 720). The appendix had appeared earlier as a paper published in Transactions of the Royal Society of Edinburgh (W. Thomson 1862). For more on the implications of Thomson’s theory for CD’s work, see Burchfield 1990, pp. 70–80.
CD refers to James Croll and to ‘On geological time, and the probable date of the glacial and the upper Miocene period’ (Croll 1868). Croll does not quote Thomson directly but refers in some detail to Thomson’s argument concerning the limit to the age of the sun’s heat (Philosophical Magazine 4th ser. 35: 368–71). Croll had sent CD a copy of the paper (see letters to James Croll, 19 September 1868 and 24 November 1868).
Samuel Haughton discussed the age of the earth and Thomson’s argument about the sun’s heat in his Manual of geology (Haughton 1865, pp. 79–95).
The reference is to Charles Lyell and Lyell 1867–8. See letter from G. H. Darwin, 8 December 1868 and n. 3. Lyell does not refer to Haughton’s views on the age of the earth or Thomson’s theory.
See letter from James Croll, 2 December 1868 and n. 2. For the abstract, see the letter from James Croll, [2 December 1868]. According to Emma Darwin’s diary (DAR 242), George went to Wales on 16 December 1868.
CD had claimed in Origin, p. 307, that life existed before the Silurian period.
CD refers to Richard Owen and the ‘derivative theory’ (see letter from G. H. Darwin, 8 December 1868 and n. 6).
CD refers to the fifth edition of Origin (see letter to J. D. Hooker, 26 November [1868].


Burchfield, Joe D. 1990. Lord Kelvin and the age of the earth. With a new afterword. Chicago and London: University of Chicago Press.

Croll, James. 1868. On geological time, and the probable date of the Glacial and the Upper Miocene Period. Philosophical Magazine 4th ser. 35: 363–84; 36: 141–54, 362–86.

Darwin pedigree: Pedigree of the family of Darwin. Compiled by H. Farnham Burke. N.p.: privately printed. 1888. [Reprinted in facsimile in Darwin pedigrees, by Richard Broke Freeman. London: printed for the author. 1984.]

Haughton, Samuel. 1865. Manual of geology. London: Longman, Green, Longman, Roberts, and Green.

Lyell, Charles. 1867–8. Principles of geology or the modern changes of the earth and its inhabitants considered as illustrative of geology. 10th edition. 2 vols. London: John Murray.

Origin: On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life. By Charles Darwin. London: John Murray. 1859.


Asks GHD to look in William Thomson’s book [W. Thomson and P. G. Tait, Treatise on natural philosophy, vol. 1 (1867)] to see how many million years ago Thomson says earth’s crust solidified. CD is troubled by "brevity of the world", because pre-Silurian creatures must have lived during endless ages "else my views wd be wrong, which is impossible – Q.E.D.".

Letter details

Letter no.
Charles Robert Darwin
George Howard Darwin
Sent from
Source of text
DAR 210.1: 6
Physical description
ALS 4pp †

Please cite as

Darwin Correspondence Project, “Letter no. 6496,” accessed on 4 June 2023,

Also published in The Correspondence of Charles Darwin, vol. 16