s commonly defined to be that branch of knowledge which considers the powers and properties of natural bodies, and their mutual actions on one another. This term serves to indicate, not one, but a cluster of sciences. Those generally comprehended under it are the following, viz. 1. Mechanics; 2. Hydrostatics; 3. Optics; 4. Astronomy; 5. Magnetism; 6. Electricity. There are, in this work, distinct treatises on all these different branches, introduced in the order of the alphabet; whilst the history of the whole is traced, in a connected method, in the second Preliminary Disserta- tion, contained in our first volume. In connection with the foregoing articles, the reader is also referred to those on Philosophy and Physics, for some general views respect- ing the nature of philosophy, and the proper manner of philosophizing.