AIDS IN OTHER PURSUITS. 
213 
ent strata in a colliery may thus be identi¬ 
fied in cases where there is no perceptible 
variation in mineral structure."^ 
The chemist discovers in the changes from 
the living plant into peat^ jet^ asphalte, bit¬ 
umen^ anthracite^ and coal, abundant sub¬ 
jects for his investigation ; and he is led to 
attempt the useful imitation of processes so 
beneficial to man, as those which are carried 
on in the great subterranean laboratory of 
the earth. 
The historian^ in these ancient inscriptions 
finds the chronology of events otherwise 
beyond his province, and is enabled to give 
* Mr. Mammatt thus relates an occurrence in the history of the 
Ashby collieries. “ During the workings, great difficulty was ex¬ 
perienced in passing faults, in finding the coal again, and in driving 
adits the shortest way to it. Here it was, that the very important 
doctrine of Mr. William Smith, came to be of the greatest prac“ 
tical use. By observing the particular fossil plants in the several 
strata, the manager was enabled to trace the height or depth to 
which the dislocated beds had passed. By this method, not only 
an immense expense was saved, but the operations were rendered 
almost certain. Many of the alternating seams were so nearly 
alike in structure, colour and density, as to be scarcely distinguish¬ 
able ; but the fossil plants or impressions, wherever they could be 
seen and examined carefully, indicated the particular stratum.'^- 
MammaWs Geological Facts, 1836. 
X 
