The same camera should be used,--so far as possible,--at a fixed distance. Our friend, who is giving us so many interesting figures in his "Trees of America," must not think this Prospectus invades his province; a dozen portraits, with lively descriptions, would be a pretty complement to his larger work, which, so far as published, I find excellent. If my plan were carried out, and another series of a dozen English trees photographed on the same scale, the comparison would be charming. It has always been a favorite idea of mine to bring the life of the Old and the New World face to face, by an accurate comparison of their various types of organization. We should begin with man, of course; institute a large and exact comparison between the development of _la pianta umana_, as Alfieri called it, in different sections of each country, in the different callings, at different ages, estimating height, weight, force by the dynamometer and the spirometer, and finishing off with a series of typical photographs, giving the principal national physiognomies. Mr. Hutchinson has given us some excellent English data to begin with. Then I would follow this up by contrasting the various parallel forms of life in the two continents. Our naturalists have often referred to this incidentally or expressly; but the _animus_ of Nature in the two half-globes of the planet is so momentous a point of interest to our race, that it should be made a subject of express and elaborate study. Go out with me into that walk which we call _the Mall_, and look at the English and American elms. The American elm is tall, graceful, slender-sprayed, and drooping as if from languor. The English elm is compact, robust, holds its branches up, and carries its leaves for weeks longer than our own native tree. Is this typical of the creative force on the two sides of the ocean, or not? Nothing but a careful comparison through the whole realm of life can answer this question.