To Charles Lyell   12 October [1866]1

Down

Oct 12

My dear Lyell

I have read all the sheets (returned by this post) with nothing less than enthusiastic admiration. I do not think you have ever published any thing better than these amended chapters.2 I began to mark, thinking that you wd like to hear, the passages which struck me most, but I soon desisted for I found I shd have to score so much. I do not suppose that you care for any criticisms on these corrected chapters, & indeed I have none worth sending. Nevertheless I will make 2 or 3 remarks.

p. 188. I am rather sorry you did not limit the remark about the increased severity of the climate destroying the mammoth as acting through the vegetation; for is it not known that they survived in America the coldest period?3

Slip p. 14. I cannot but think that the marked passage is too strong. Any one with your knowledge & skill cd make out a striking case on the permanence of our continents,—from the continuity of allied terrestrial forms on the same continent,—from the dissimilarity of the marine Fauna during the present & past tertiary ages on the opposite sides of some continents,—& from the present distribution of mammals & indeed of all organic beings.4

slip 15. Is not this line bold, not to say rash; seeing that in the islands of the great oceans we have not a fragment of any secondary or even true Plutonic rock?5

I wish you joy at having so nearly completed this extremely difficult part of your work; & as far as I can judge it is admirably completed.6

yours affectionately | Ch. Darwin

P.S. The passage about the evaporation of the Snow, which is only conjectural, though I have no doubt that the fact was correctly reported, is at p. 245 of my Journal, in a note to passage about the great curvature of the snow-line.—7

P.S. Did you know that according to Airy, Adams & others (as stated in Prichards Pres. Astronom. Soc. in his Nottingham sermon) the day is slowly increasing in length; so that a million x million years ago it must have been only the 1200 th part of a second in length! & in the same period in futurity, each day will be 80 years in length.—8

LS(A)

1
The year is established by the relationship between this letter and the letter to Charles Lyell, 9 October [1866].
2
Lyell had sent CD proof-sheets of the first volume of the tenth edition of Principles of geology (C. Lyell 1867–8). In addition to several minor alterations, he had re-written three chapters and added two new ones (for a list of the revisions, see C. Lyell 1867–8, 1: iii–v). CD had already commented on changes to chapter 9, concerning the development of organic life (see letter to Charles Lyell, 9 October [1866] and nn. 4–6).
3
Lyell argued that the disappearance of animals like the mammoth could be explained without resorting to speculation about sudden climate change; he proposed that a moderate decrease in temperature would result in a diminution of vegetation, which in turn would cause the extinction (C. Lyell 1867–8, 1: 187–8).
4
It is not clear to which passage CD is referring, as the proof-sheets he marked have not been found. In the printed version, Lyell argued that even though present continents had existed since long before the Eocene, the fossil record indicated that the distribution of land and sea during the Eocene must have been vastly different (C. Lyell 1867–8, 1: 253–5). For earlier arguments between CD, Lyell, and Joseph Dalton Hooker on the possible changes of land and water surface areas and their potential effect on climate change, see, for example, Correspondence vol. 12, letter to J. D. Hooker, 23 October [1864] and n. 10; see also Ospovat 1977.
5
The passage referred to has not been identified, but see C. Lyell 1867–8, 1: 142–5 for Lyell’s discussion of the characteristics and origin of plutonic and metamorphic rocks.
6
The first volume of C. Lyell 1867–8 was advertised in Publishers’ Circular, 15 November 1866, p. 722. CD’s lightly annotated copy, signed and dated 29 November 1866 by the author, is in the Darwin Library–CUL (see Marginalia 1: 543–4).
7
In the printed version of C. Lyell 1867–8, Lyell included this reference to the second edition of Journal of researches to support the view that snow and ice could evaporate in cold, dry regions without first becoming liquid (see C. Lyell 1867–8, 1: 286–7).
8
CD refers to George Biddell Airy, John Couch Adams, and Charles Pritchard, who was president of the Royal Astronomical Society in 1866 (DNB). In his sermon at the meeting of the British Association for the Advancement of Science (see letter from Charles Pritchard, 8 October 1866 and nn. 1 and 2), Pritchard had cited recent astronomical calculations indicating that the length of a day was constantly increasing. He suggested that if CD were right about the great age of the earth, then at the earliest times, a day would have been a fraction of a second in length (see C. Pritchard 1866, pp. 35–6).

Manuscript Alterations and Comments

5.1 at] in CD’s hand above del ‘of’
6.1 Ch. Darwin … length.—- 8.5] in CD’s hand

Please cite as “DCP-LETT-5239,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-5239