873. The trees of America have been described by Michaux. The number of these which grow above thirty feet high, and which he has seen and described, is one hundred and thirty-seven, of which eighty-five are employed in the arts. In France there are only thirty-seven which rise to that height, of which eighteen serve to form timber plantations, and of these seven only are employed in civil and marine constructions Michaux acknowledges his obligations to W. Hamilton, 'an enlightened amateur of the sciences and arts,' who pleased himself in uniting at his magnificent residence at Woodlands, near Philadelphia, not only all the useful vegetables of the United States, but those of every country of the world, which may offer any interest in the arts or in medicine. This residence, in 1843, was converted into a cemetery.