The question you suggest as to the effect of the destruction of the forests on the climate is very interesting, and I think still unanswered. I fear it will be next to impossible to obtain data, even in this country, for its satisfactory determination. There are very few thermometrical observations on record of sufficient extent or exactness, except for the last eight or ten years. For a year or two I shall not be able to pay any attention to these subjects except to collect materials. But I am very desirous to afford you any aid in my power, and will attend to any suggestions you make, obtain any data which come in my way, or secure the services of our botanical correspondents scattered throughout our extended country. Pray tell me how I can aid you. The annual reports of the regents of the University of the State of New York are documents submitted annually to our legislature, and printed at their expense for public use. They relate chiefly to the condition of our colleges and higher schools, but for six or perhaps nine years past have also embodied the results of the meteorological observations made throughout the State under their instructions. The “Reports” are not on sale, and the earlier numbers are not to be obtained except by some lucky chance.... The 3d and 4th parts of our “Flora,” of which you speak so favorably, were sent to you through Baron Delessert, as I have already apprised you. By the time this work is completed we shall have settled somewhat accurately the geographical range of our plants, and have laid a good foundation for the comparison of our flora with that of other regions, etc. We shall soon begin to print the “Compositæ,” and I trust in early spring we may see the second volume nearly or quite completed. Pray send me sometimes loose sheets of your articles or notices (those of your father and yourself) in the “Bibliothèque Universelle.” I will sometimes translate them, if you do not object, or otherwise notice them, for the “American Journal of Science and Arts.” TO W. J. HOOKER. NEW YORK, 15th January, 1841. The dedication of the “Flora” we felt to be both a privilege and a duty; its favorable reception on your part gives us real pleasure.