X INTRODUCTION. 
to investigate the mutual agencies of the elementary principles of mat- 
ter upon one another, their composition, and the laws by which they 
are regulated. These divisions of the great field of Natural Science 
have, from the universality of their influence, been called General 
Physics ; while Natural History, in its limited sense, and as confined 
to the examination of what have been called the three kingdoms of 
Nature, viz: the Animal, Vegetable, and Mineral, has received the 
name of Particular Physics. Natural History, besides, is distinguished 
from the other branches of science now named in this, that while Dy- 
namics is a science chiefly of calculation, and Chemistry of experi- 
ment, the basis of this science rests chiefly on observation. 
In the limited sense in which Natural History is thus to be under- 
stood, as confined to the three great divisions of Animals, Vegetables, 
and Minerals, a System of Nature is a grand catalogue of the objects 
in these kingdoms, in which each individual has a distinctive charac- 
ter and an appropriate name. ‘These individuals, for the sake of ar- 
rangement, are collected into groups, which have something im com- 
mon, and which are termed Genera; genera are further combined into 
other groups, which form in systems what are called Orders; and or- 
ders are finally arranged under one great head, which is termed a 
Class. This scale of divisions, of which the highest contains the least, 
is, as Baron Cuvier remarks, a kind of dictionary, where the properties 
of things are investigated to discover their names, and which rz veises 
the usual order of such works, where the names are indicated az de- 
tailing the qualities of the things named. 
But though method and arrangement form the first step to th. ruow- 
ledge of the numerous objects which claim the attention of ti. "atu- 
ralist, Natural History is by no means confined to a list of names. If 
the method be a good one, and the subdivisions arranged con./oraably 
to the fundamental and natural connections of bodies, the very arrarze- 
ment and classification of names of beings which have som :thing in 
common, leads to the knowledge of their connection and di yendence 
upon one another, and to their comparative importance in th? scale of 
existence. Were it possible to arrange all the classes of organized ana 
inorganized existence in such a manner that the individuals of the 
same genus should be more nearly connected with that genus than 
with any other—the genera of the same order more nearly connecteu 
with that order than with ali the other orders, and so on,—little rnore 
would be necessary to make the method, so far as depends on arrange- 
ment, camplete. But it has not hitherto been found in practice, that 
