To A. B. Buckley   18 December [1871]1

6 Queen Anne St.

Dec. 18th.

My dear Miss Buckley

I am very much obliged to you for your note and the proof-sheets herewith returned.2 I fear I may have been rash, but what I can do to make things better I do not know till I consider my proof-sheets.3 I have no brains in London.—

I have not read all the sheets only the parts (and a little more) which you have marked. I remember Mr. Croll in a letter to me attributed the greatest influence to the sea-currents in causing the colder and warmer opposite hemispheres.—4 I see that I ought (whether or not I have, I cannot remember) not to have even alluded to glacial periods without alluding to the distribution of Land and Water.— It is not so much the simple non-destruction of Tropical productions, but the good evidence, as it seems to me, of a former temperate climate having prevailed recently over all equatorial lands and the apparent impossibility of the tropical forms having survived unless they had some refuge. It is this which has made me so strongly inclined to believe in opposite climates in the two hemispheres.5

Pray forgive this dreadfully obscure note; but I have no brains and my hand is unsteady. | With very many thanks | Your’s sincerely | Ch. Darwin

Copy

1
The year is established by the address. CD was in London from 14 to 22 December 1871 (see ‘Journal’ (Appendix II)).
2
Buckley’s note and the proof-sheets have not been found; they were evidently proof-sheets of the eleventh edition of Charles Lyell’s Principles of geology (Lyell 1872).
3
CD refers to proof-sheets for the sixth edition of Origin, which he finished working on by 10 January 1872 (see Correspondence vol. 20, ‘Journal’ (Appendix II)). For CD’s alterations to Origin 6th ed. in response to Lyell, see n. 5, below.
4
In his paper ‘On geological time, and the probable date of the glacial and the upper Miocene period’ (Croll 1868, pt 3, p. 379), James Croll suggested that every ten to twelve thousand years, conditions of climate reversed in the two hemispheres. When CD asked for clarification (see Correspondence vol. 16, letter to James Croll, 24 November 1868 and n. 5), Croll responded with an abstract of his views in which he wrote, ‘the most powerful of all the causes is that resulting from the influence that excentricity has upon ocean currents’ (see Correspondence vol. 16, letter from James Croll, [2 December 1868]). In Origin 5th ed., p. 451, CD added a discussion of Croll’s work and noted, ‘the most powerful [cause of glaciation] appears to be the influence of the excentricity of the orbit upon oceanic currents’.
5
In Lyell 1872, 1: 277–80, Lyell argued that Croll had not given enough weight to geographical causes, noting that the severity of cold was influenced by the distribution of land and sea. Lyell further remarked, citing the discussion in Origin 5th ed., that although CD seemed inclined to accept Croll’s theory of alternate cold periods in the hemispheres as a way of explaining the survival of tropical plants during cold periods, other factors could account for their persistence (ibid., pp. 283–4). In Origin 6th ed., p. 336, CD maintained his support for Croll’s theory, but added, ‘According to Mr. Croll, cold periods regularly recur every ten or fifteen thousand years; and these at long intervals are extremely severe, owing to certain contingencies, of which the most important, as Sir C. Lyell has shown, is the relative position of the land and water.’

Please cite as “DCP-LETT-6508,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-6508