this edition, especially the second part, which I have just finished. I have added a good deal about the Fuegians, and cut down into half the mercilessly long discussion on climate and glaciers, etc. I do not recollect anything added to the first part, long enough to call your attention to; there is a page of description of a very curious breed of oxen in Banda Oriental. I should like you to read the few last pages; there is a little discussion on extinction, which will not perhaps strike you as new, though it has so struck me, and has placed in my mind all the difficulties with respect to the causes of extinction, in the same class with other difficulties which are generally quite overlooked and undervalued by naturalists; I ought, however, to have made my discussion longer and shewn by facts, as I easily could, how steadily every species must be checked in its numbers. I received your Travels ('Travels in North America,' 2 volumes, 1845.) yesterday; and I like exceedingly its external and internal appearance; I read only about a dozen pages last night (for I was tired with hay-making), but I saw quite enough to perceive how VERY much it will interest me, and how many passages will be scored. I am pleased to find a good sprinkling of Natural History; I shall be astonished if it does not sell very largely... How sorry I am to think that we shall not see you here again for so long; I wish you may knock yourself a little bit up before you start and require a day's fresh air, before the ocean breezes blow on you... Ever yours, C. DARWIN. CHARLES DARWIN TO C. LYELL. Down, Saturday [August 1st, 1845]. My dear Lyell, I have been wishing to write to you for a week past, but every five minutes' worth of strength has been expended in getting out my second part. (Of the second edition of the 'Journal of Researches.') Your note pleased me a good deal more I dare say than my dedication did you, and I thank you much for it. Your work has interested me much, and I will give you my impressions, though, as I never thought you would care to hear what I thought of the non-scientific parts, I made no notes, nor took pains to remember any particular impression of two-thirds of the first volume. The first impression I should say would be with most (though I have literally seen not one soul since reading it) regret at there not being more of the non-scientific [parts]. I am not a good judge, for I have read nothing, i.e. non-scientific about North America, but the whole struck me as very new, fresh, and interesting. Your discussions bore to my mind the evident stamp of matured thought, and of conclusions drawn from facts observed by yourself, and not from the opinions of the people whom you met; and this I suspect is comparatively rare.