The Brief Synopsis of Appendix I. Is intended to facilitate the use of this Manual as a recitation-book. Lectures cannot well be wholly dispensed with in the instruction of Natural or Physical Science; but, with a work so full of illustrations as this, they may, with great advantage, be altogether subordinate to recitations, espe cially if the latter are accompanied with an exhibition of speci mens. Through the use of fine type for the details of the Science, the Manual is made to combine in one a small and a large book. The topics presented in the Synopsis are, with few exceptions, those of the former; and they are so prepared that each suggests a question. A cursory perusal of the details in the smaller type is, however, to be advised, as it will aid the student in acquiring precise ideas. Even in scientific schools it may be best that the student first go through the Manual with the Synopsis, and then, in a second course, take up the Palaeontology and Dynamics with greater thoroughness. Every Academy or other Institution teaching the Science should have, at least, a small collection of specimens. Even twenty-five dollars will purchase one (of Louis Seemann, Paris, 45 Rue St. Andre des-arts, or of Dr. A. Krantz, at Bonn on the Rhine) containing specimens of nearly all the mineral species mentioned in the Manual, and of the more common kinds of rocks, and another twenty-five dollars, a collection of fossils that would be of great service.