When my book on Volcanoes and Coral Reefs will be published I hardly know; I fear it will be at least four or five months; though, mind, the greater part is written. I find so much time is lost in correcting details and ascertaining their accuracy. The Government Zoological work is a millstone round my neck, and the Glen Roy paper has lost me six weeks. I will not, however, say lost; for, supposing I can prove to others' satisfaction what I have convinced myself is the case, the inference I think you will allow to be important. I cannot doubt that the molten matter beneath the earth's crust possesses a high degree of fluidity, almost like the sea beneath the block ice. By the way, I hope you will give me some Swedish case to quote, of shells being preserved on the surface, but not in contemporaneous beds of gravel... Remember what I have often heard you say: the country is very bad for the intellects; the Scotch mists will put out some volcanic speculations. You see I am affecting to become very Cockneyfied, and to despise the poor country-folk, who breath fresh air instead of smoke, and see the goodly fields instead of the brick houses in Marlborough Street, the very sight of which I confess I abhor. I am glad to hear what a favourable report you give of the British Association. I am the more pleased because I have been fighting its battles with Basil Hall, Stokes, and several others, having made up my mind, from the report in the "Athenaeum", that it must have been an excellent meeting. I have been much amused with an account I have received of the wars of Don Roderick (Murchison.) and Babbage. What a grievous pity it is that the latter should be so implacable...This is a most rigmarole letter, for after each sentence I take breath, and you will have need of it in reading it... I wish with all my heart that my Geological book was out. I have every motive to work hard, and will, following your steps, work just that degree of hardness to keep well. I should like my volume to be out before your new edition of 'Principles' appears. Besides the Coral theory, the volcanic chapters will, I think, contain some new facts. I have lately been sadly tempted to be idle--that is, as far as pure geology is concerned--by the delightful number of new views which have been coming in thickly and steadily,--on the classification and affinities and instincts of animals--bearing on the question of species. Note-book after note-book has been filled with facts which begin to group themselves CLEARLY under sub-laws. Good night, my dear Lyell. I have filled my letter and enjoyed my talk to you as much as I can without having you in propria persona. Think of the bad effects of the country--so once more good night. Ever yours, CHAS. DARWIN. Pray again give my best thanks to Mrs. Lyell.