COAL. 
461 
most abundantly provided with mines of coal, as if 
Nature was determined to second the exertions of 
an industrious people by giving them the best pos- 
sible assistance. 
The form and uses of coal are too well known to 
require any description ; we shall therefore confine 
ourselves to an account of its disposition in the 
bowels of the earth, and to some of the principal 
collieries in different parts of Europe. 
Coal is always found in masses, sometimes in a 
heap, most frequently in beds ; but rarely in veins. 
The beds are disposed within the eai'th with differ- 
ent degrees of inclination, and in almost every pos- 
sible direction. These beds of coal are supposed 
by most naturalists to be a deposit formed by the 
waters of the ocean, which once covered our con- 
tinent. They are never found single, but generally 
disposed in strata one above another. The beds of 
coal are separated by layers of stone, which are 
nearly of the same nature in all coal-mines. Those 
which form the side and the top of a stratum of 
coal are a sort of friable slate, containing more or 
less of bitumen, while the bottom is generally 
more compacted and mixed with micaceous sand. 
It is remarkable that this slaty kind of stone, which 
so generally accompanies the coal, should frequently 
contain the impressions of plants, and particularly 
ferns, some of which are met with in the finest state 
of preservation. 
Patrin informs us that the coal-mines in France 
are generally surrounded by primitive rocks, espe- 
