12 OBJECTS AND METHODS OF GEOLOGY. 
History. Theoretical Geology, occupied in the investigation and 
discovery of causes from their effects, belongs to Natural Philoso- 
phy. But as many of the doctrines of the latter are derived from 
the characters presented by organic remains, the connexion 
between it and one department of Natural History is very inti- 
mate. It is of importance to the modern geologist that he be well 
versed in the science of conchology. Positive Geology, which 
ascertains the facts on which many of the conclusions of the 
other are founded and built, will demand our earliest attention ; 
but in this science more than in most others, it is necessary to 
bring forward facts, points of theory, and historical details, by 
turns and in succession. Facts of first rate importance in the il- 
lustration of our theories, are without interest when their bearing 
upon the great doctrines of the science is not apparent, and not 
only have opinions once generally held, but now abandoned, left 
their impress upon the language it employs, but some ac- 
quaintance with them is necessay to a correct understanding of 
the works on Geology that are published in our own day, and of 
the views entertained by the philosophers of the present age. — 
A few general statements on the whole subject are first to be pre- 
sented and some terms explained. 
Astronomy, relating to bodies separated from us by an interval 
(with a single exception) of several millions of miles, is the most 
ancient, and Geology, having for its object the earth on which 
we live, one of the more recent of the sciences. Nor is this re- 
markable. The magnificence of the starry heavens drew to them 
the attention of the early inhabitants of the earth. A connexion 
was observed between the aspect of the sky, and the changes of the 
seasons, the rising and setting of certain constellations, and the 
return of spring or summer. The same tablet was spread out 
for observation and study before thousands of curious and watch- 
ful eyes on successive nights. It was soon ascertained that some 
of the stars always maintain the same relative position, whilst 
others wander through the whole circle of the heavens, and thus 
the first foundations of Astronomy were laid. The earth on the 
other hand, seemed to present little more than a shapeless chaos 
as rocks and mountains, without beauty, or order, or value, except 
to affording a dwelling place for man and other animals, and 
nourishment for the vegetables used by them for food, and was 
therefore neglected. 
It is true that men had hardly begun to reason, before they be- 
gan to speculate about the manner in which the world was formed ; 
but they were not careful to establish their theories on a basis of 
fact and observation. Years rolled on; in other departments of 
knowledge vast accumulations were made, but Cosmogony — the 
science of creating worlds, or showing how they might be generat- 
ed or made, remained stationary, or nearly so, for many years. 
Bacon appeared teaching the correct method of philosophising, 
and Newton revealing the secret mechanism of the heavens j but 
