INTRODUCTION. 



As correct ideas respecting Natural History are not very generally 

 formed, it appears necessary to begin by denning its peculiar object, 

 and establishing rigorous limits between it and neighbouring sciences. 



In our language, and in most others, the word NATURE is variously 

 employed. At one time it is used to express the qualities a being de- 

 rives from birth, in opposition to those it may owe to art ; at another, 

 the entire mass of beings which compose the universe ; and at a third, 

 the laws which govern those beings. It is in this latter sense parti- 

 cularly that we usually personify Nature, and, through respect, use its 

 name for that of its Creator. 



Physics, or Natural Philosophy, treats of the nature of these three 

 relations, and is either general or particular. General physics examines 

 abstractedly each of the properties of those moveable and extended beings 

 we call bodies. That branch of it, styled Dynamics, considers 

 bodies in mass ; and, proceeding from a very small number of experi- 

 ments, determines mathematically the laws of equilibrium, and those of 

 motion and of its communication. Its different divisions are termed 

 Statics, Hydrostatics, Hydrodynamics, Mechanics, &c. &c., according 

 to the nature of the particular bodies whose motions it examines. Optics 

 considers the particular motions of light, whose phenomena, which 

 hitherto nothing but experiment has been able to determine, are 

 becoming more numerous. 



Chemistry, another branch of general physics, exposes the laws by 

 which the elementary particles of bodies act on each other ; the com- 

 binations or separations which result from the general tendency of 

 these particles to re-unite ; and the modification which the various 

 circumstances capable of separating or approximating them produce on 

 that tendency. It is purely a science of experiment, and is not reducible 

 to calculation. 



