Your slave discussion disturbed me much; but as you would care no more for my opinion on this head than for the ashes of this letter, I will say nothing except that it gave me some sleepless, most uncomfortable hours. Your account of the religious state of the States particularly interested me; I am surprised throughout at your very proper boldness against the Clergy. In your University chapter the Clergy, and not the State of Education, are most severely and justly handled, and this I think is very bold, for I conceive you might crush a leaden-headed old Don, as a Don, with more safety, than touch the finger of that Corporate Animal, the Clergy. What a contrast in Education does England show itself! Your apology (using the term, like the old religionists who meant anything but an apology) for lectures, struck me as very clever; but all the arguments in the world on your side, are not equal to one course of Jamieson's Lectures on the other side, which I formerly for my sins experienced. Although I had read about the 'Coalfields in North America,' I never in the smallest degree really comprehended their area, their thickness and favourable position; nothing hardly astounded me more in your book. Some few parts struck me as rather heterogeneous, but I do not know whether to an extent that at all signified. I missed however, a good deal, some general heading to the chapters, such as the two or three principal places visited. One has no right to expect an author to write down to the zero of geographical ignorance of the reader; but I not knowing a single place, was occasionally rather plagued in tracing your course. Sometimes in the beginning of a chapter, in one paragraph your course was traced through a half dozen places; anyone, as ignorant as myself, if he could be found, would prefer such a disturbing paragraph left out. I cut your map loose, and I found that a great comfort; I could not follow your engraved track. I think in a second edition, interspaces here and there of one line open, would be an improvement. By the way, I take credit to myself in giving my Journal a less scientific air in having printed all names of species and genera in Romans; the printing looks, also, better. All the illustrations strike me as capital, and the map is an admirable volume in itself. If your 'Principles' had not met with such universal admiration, I should have feared there would have been too much geology in this for the general reader; certainly all that the most clear and light style could do, has been done. To myself the geology was an excellent, well-condensed, well-digested resume of all that has been made out in North America, and every geologist ought to be grateful to you. The summing up of the Niagara chapter appeared to me the grandest part; I was also deeply interested by your discussion on the origin of the Silurian formations. I have made scores of SCORES marking passages hereafter useful to me.