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INTRODUCTION. 
1 
OF NATURAL HISTORY, AND OF SYSTEMS GENERALLY. 
As few persons have a just idea of Natural History, it appears necessary to com- 
mence our work by carefully defining the proposed object of this science, and establish- 
ing rigorous limits between it and the contiguous sciences. 
The word Nature, in our language, and in most others, signifies sometimes, the 
qualities which a being derives from birth, in opposition to those which it may 
owe to art ; at other times, the aggregate of beings which compose the^ universe ; 
and sometimes, again, the laws which govern these beings. It is particularly in 
this latter sense that it has become customary to personify Nature, and to employ 
the name, respectfully, for that of its Author. 
Physics, or Natural Philosophy, treats of the nature of these three relations, and is 
either ereneral or particular. General Physics examines, abstractedly, each of the 
properties of those moveable and extended beings which we call bodies. That depart- 
ment of them styled Dynamics, considers bodies in mass ; and, proceeding from a very 
small number of experiments, determines mathematically the laws of equilibrium, and 
those of motion and of its communication. It comprehends in its different divisions 
the names of Statics, Mechanics, Hydrostatics, Hydrodynamics, Pneumatics, &c., ac- 
cording to the nature of the bodies of which it examines the motions. Optics considers 
the particular motions of light ; the phenomena of which, requiring experiments for 
their determination, are becoming more numerous. 
Chemistry, another branch of General Physics, expounds the laws by which the 
elementary molecules of bodies act on each other when in close proximity, the com- 
binations or separations which result from the general tendency of these molecules to 
unite, and the modifications which different circumstances, capable of separating or 
approximating them, produce on that tendency. It is a science almost wholly ex- 
perimental, and which cannot be reduced to calculation. 
The theory of Heat, and that of Electricity, belong almost equally to Dynamics or 
Chemistry, according to the point of view in which they are considered. 
The method which prevails in all the branches of General Physics consists in 
isolating bodies, reducing them to their utmost simplicity, in bringing each of their 
properties separately into action, either mentally or by experiment, in observing or 
calculating the results, in short, in generalizing and correcting the laws of these pro- 
