My dear Lyell,

I was delighted to receive your letter, which was forwarded here to me. I am very glad to hear about the new Edit of the Principles,¹ & I most heartily hope you may live to bring out half-a-dozen more editions. There would not have been such books as d’Orbignys S. American Geology² published, if there had been seven Editions of the Principles distributed in France. I am rather sorry about the small type; but the first Edit, my old true-love,³ which I never deserted for the later editions, was also in small type.— I much fear I shall not be able to give any assistance to Book III;⁴ I think I formerly gave my few criticisms, but I will read it over again very soon (though I am slaving to finish my S. American Geolog) & see whether I can give you any references.—

I have been thinking over the subject, & can remember no one book of consequence, as all my materials (which are in an absolute chaos on separate bits of paper) have been picked out of books not directly treating of the subjects you have discussed, & which I hope some day to attempt: thus Hooker’s Antarctic Flora,⁵ I have found eminently useful & yet I declare I do not know what precise facts I could refer you to. Bronn’s Gesichte⁶ (which you once borrowed) is the only systematic book I have met with on such subjects; & there are no general views in such parts, as I have read, but an immense accumulation of references, very useful to follow up, but not credible in themselves;—thus he gives hybrids from ducks & fowls just as readily as between fowls & pheasants! you can have it again, if you like.— I have no doubt Forbes essay, which is I suppose now fairly out, will be very good under geographical head.⁷ Koelreuter’s German Book⁸ is excellent on Hybrids, but it will cost you a good deal of time to work out any conclusions from his numerous details. With respect to variation, I have found nothing, but minute details scattered over scores of volumes.— But I will look over Book III again: What a quantity of work you have in hand! I almost wish you c^d have finished America,⁹ & thus have allowed yourself rather more time for the old Principles, & I am quite surprised that you c^d. possibly have worked your own new matter in within six weeks. Your intention of being in Southampton will much strengthen mine & I shall be very glad to hear some of your American Geolog. news.—¹⁰

You have pleased me much by saying that you intend looking through my Volcanic volume: it cost me 18 months!!! work & I have heard of very few who has read it; now I shall feel whatever little (& little it is) there is confirmatory of old work or new will work its effect & not be lost. I wish my S. American volume was out for same end, & I daresay you will be heartily glad it is not, for you must with all your work in hand, grudge time for your own new materials. I sh^d. have liked to have had your opinion on my facts & short discussion regarding the foliation of the metamorphic schists,¹¹ which I am now correcting;—and another on the absence of recent conchiferous deposits & on the tertiary formations having been deposited during subsidence:¹² but I will have mercy on you & say no more on my volume, of which I am inexpressibly weary & thank Heavens have now finally corrected $\frac{2}{3}$ of, & hope to see published this month.

I return home on Tuesday, having been here for a week to see my Father: Emma & the children have been having colds but are otherwise well.— I hope you found M^r & M^rs Lyell tolerably well.— How I shall enjoy having you for a visit to Down & I believe you c^d with quiet & fresh air do more work with us than in that horrid place London.—

I must go to work to proof-sheets: my vol will be about 240 pages, dreadfully dull yet much condensed: I think, whenever you have time to look through it, you will think the collection of facts on the elevation of the land & on the formation of terraces pretty good.

Goodbye with many thanks for your letter & my kindest remembrances to M^rs Lyell. | Ever yours | C. Darwin