It has a large gratuitous distribution, both at home and abroad, and an extensive good-will exchange with works often having no particular bearing upon its peculiar objects. It has incurred a heavy extra expenditure in reprinting exhausted numbers, for the purpose of furnishing entire sets of the work. No application for an entire set has ever yet been disappointed, and complete sets of the volumes are to be found in many institutions and in the hands of many individuals, both in Europe and in the United States. Entire sets have often been presented gratuitously to our infant colleges and to scientific institutions and distinguished individuals in Europe. A few remain on hand, and it is our intention to furnish them as long as we can afford to republish, or can repurchase numbers that have run out. * * * * * The series of volumes must ever form a work of permanent interest on account of its exhibiting the progress of American science during the long period which it covers. Comparing 1817[C] with 1847, we mark on this subject a very gratifying change. The cultivators of science in the United States were then few--now they are numerous. Societies and associations of various names, for the cultivation of natural history, have been instituted in very many of our cities and towns, and several of them have been active and efficient in making original observations and forming collections. The American Philosophical Society at Philadelphia, the American Academy of Arts and Sciences at Boston, and the Academy of Natural Sciences also at Philadelphia, numbered distinguished names among their members, and had published valuable volumes of Transactions before our publication began. The Connecticut Academy of Arts and Sciences had also published a single volume as early as 1813. Since that time the Lyceum of Natural History of New York, the Boston Society of Natural History, the Albany Institute, and the Maryland Academy of Sciences have stood prominent among associations of a like nature, and their memoirs now constitute an important item in our scientific history. Other associations for the departments of history and ethnography have also published memoirs; and we must not omit to mention the American Geological Society, and the Geological Society of Pennsylvania, which has issued one valuable volume.