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that it seemed as if you had discovered another world, just beneath 
the crust of that which you had lately quitted. There can undoubt- 
edly be hardly any scene, which can be presented to the view, 
capable of exciting more astonishment than the one you describe. 
Wonderful indeed must have been the scene, after a dark and 
dreary descent through so many fathoms of dripping strata, which 
must have offered itself, when you made your entrance into a cavern 
from which the glimpse of day was excluded ; where the roof, the 
floor, and the walls, presented every where to the eye the same 
jetty black ; except where the oozing drop, or the brilliant spar or 
marcasite, reflected the flames of the lamps ; which, disposed in 
various parts, lighted the inhabitants of these seeming Vulcanian 
regions to their labours. These, as you inform me, were separating 
with their ponderous instruments, into fragments of a convenient 
size, parts of the immense mass of coal, which years and years of 
labour had seemed to have left inexhaustible. Such an assemblage 
of striking and entirely novel appearances, could not fail of exciting 
a train of thoughts widely different from any your mind had yet 
known, and must necessarily have rendered you anxious to gain 
some information as to the history of these regions. This part, as 
well as the rest, of my engagement, I shall perform with the utmost 
readiness, pleased with the idea that I may thus render your de- 
lightful tour more interesting and instructive. 
Common coal, that substance so eminent for its utility to man as 
an article of fuel, is the fossil which therefore shall next claim our 
attention. 
Coal is a black, solid, and compact substance, generally of a 
foliated or rather laminated structure, which necessarily directs its 
fracture. Its specific gravity is 1.25 to 1.3/. It possesses a moderate 
degree of hardness, but is more brittle than Cannel coal; than 
which it also takes fire less readily, and is longer in consuming. It 
cakes into cinders more or less during its combustion, accordsng to 
