4 
eesse to regard as dangerous, and tlie disturbers of truth, those 
who follow to the utmost the legitimate investigations in physics 
and natural history opened out by the comprehensive labours 
of the geologist. 
No science, save chemistry, has in the same short time made 
such rapid advances as geology. While the former began to 
assume its true position under Black, Cavendish, Priestly, and 
Lavoisier, geology received a new stimulus in the grand genera- 
lization of W erner, Hutton, Cuvier, and Smith ; and of late 
years so rapid and wide-spreading has been its progress, that no 
single mind can grapple with all the details of its numerous 
branches. 
Of those the chief are : — 
1st. Physical geology. 
2nd. Palaeontology. 
The first deals with the nature and modes of formation of 
rocks, such as the laws that regulate and have regulated the 
orio-in and manner of distribution of strata, the nature ot sub- 
o 
terranean beat, its present and past effects beneath the surface 
of the globe, and the exterior igneous phenomena dependent 
on its operation ; the disintegration, slow movements, or more 
violent disturbances traceable to these, or other causes, of which 
the present configuration of land and water is the sum ; and the 
means consequently yielded by these apparent breaks in the 
continuity of order, of demonstrating the law of the superposi- 
tion of strata, and of succession in geological time. 
Here it is that palaeontology, or the history of the old life of 
the world, comes to our aid. The time is not very far removed 
when, under such names as glossopet 1*00) cockles, and petrifac- 
tions, tliose wonderful organisms that abound in rocks, were 
' <D 
confounded by the curious with crystalline and other mineral 
substances ; and though Hook had hinted at, and Fuchsel al- 
most pointed the way, it was not till William Smith clearly 
enunciated the doctrine of the characterization of masses of super- 
imposed strata by distinct groups of fossils, that their study 
acquired that scientific value by means of which the geologist 
is enabled to identify groups of strata, though broad oceans roll 
