546 
BURNING COAL MINES. 
from its original deposit might, at least locally, affect the mag¬ 
netic and electrical condition of the earth’s crust to a sensible 
degree. 
Accidental fires in mines of coal or lignite sometimes lead 
to consequences not only destructive to large quantities of val¬ 
uable material, but may, directly or indirectly, produce results 
important in geography. The coal occasionally takes fire from 
the miners’ lights or other fires used by them, and, if long ex¬ 
posed to air in deserted galleries, may be spontaneously kin¬ 
dled. Under favorable circumstances, a stratum of coal will 
burn till it is exhausted, and a cavity may be burnt out in a 
few months which human labor could not excavate in many 
years. W ittwer informs us that a coal mine at St. Etienne in 
Dauphiny has been burning ever since the fourteenth century, 
and that a mine near Duttweiler, another near Epterode, and 
a third at Zwickau, have been on fire for two hundred years. 
Such conflagrations not only produce cavities in the earth, but 
communicate a perceptible degree of heat to the surface, and 
the author just quoted cites cases where this heat has been ad¬ 
vantageously employed in forcing vegetation.* 
* PhysiJcalische Geographic , p. 168. Beds of peat, accidentally set on 
fire, sometimes continue to burn for months. I take the following account 
of a case of this sort from a recent American journal: 
“ A Curious Phenomenon. —When the track of the railroad between 
Brunswick and Bath was being graded, in crossing a meadow near the 
populous portion of the latter city, the ‘ dump ’ suddenly took on a sink¬ 
ing symptom, and down went the twenty feet fill of gravel, clay, and 
broken rocks, out of sight, and it was a long, long time before dirt trains 
could fill the capacious stomach that seemed ready to receive all the solid 
material that could be turned into it. The difficulty was at length over¬ 
come, but all along the side of the sinkage the earth was thrown up, broken 
into yawning chasms, and the surface was thus elevated above its old watery 
level. Since that time this ground, thus slightly elevated, has been culti¬ 
vated, and has yielded enormously of whatever the owner seemed disposed 
to plant upon it. Some three months ago, by some means unknown to us, 
the underlying peat took fire, and for weeks, as we had occasion to pass it, 
we noticed the smoke arising from the smouldering combustion beneath 
the surface. Rains fell, but the fire burned, and the smoke continued to 
arise. Monday we had occasion to pass the spot, and though nearly a 
