374 Copper Mines. 
from above at convenient distances to the N. or S., which. 
ever may be the inclination of the lode or layer; after which 
the same course of operation takes place as has been des- 
cribed before, and thus two floors or levels are formed; 
during which the miners from the upper floor make ap- 
proaches towards those on the second floor by excavations 
at regular distances ; after this, the intermediate parts (or 
the portions of the layer between such excavations are cut 
away, and thus the whole portion of the layer between the 
first and second floor is removed. It is obvious that in so 
large an excavation, a great extent of surface would be 
left unsupported and likely to fall in were not something 
done to prevent sucha calamity. For this purpose recourse 
is had to timber, a man being constantly at hand whose 
exclusive duty it is, to shore up those parts in the progress 
of the work, where any danger is apprehended. The tim- 
ber is usually deal, imported from the Baltic, free of duty, 
and it would be difficult for anyone wholly unacquainted 
with mining operations, to form an idea of the vast quan- 
tity which is used on such occasions. As the mine becomes 
deeper, fresh excavations are made on new levels or floors ; 
the intermediate parts of which are cast away and timbered 
in a manner similar to what has been described, In fact, 
as the work descends, it exhibits nothing but a repetition 
of operations at stated depths varying but little from one 
another until either the mine is worked out, or the expenses 
incidental to its progress are found more than equal to the 
profits. Mines are occasionally sunk to a very great depth. 
One mine in Cornwall is said to be 1,800 feet deep, with 
levels and other ramifications of proportionate extent. In 
mines newly formed the operators usually ascend and de- 
scend by buckets as before described, ‘but this would after 
a short time, be found inconvenient ; on which account a 
shaft is in generally cut on purpose for ascent and descent, - 
called a foot way to the sides of which are attached iron 
ladders. At the distance of about every 60 feet are landings 
or resting places, formed of timber, having apertures for the 
ladders made alternately in opposite directions, so that a 
person could not in case of accident easily fall beyond 60 
feet at any onetime, In the subterranean excavations, the 
workmen are plentifully supplied with candles, notwith- 
standing which there is often difficulty in procuring suf- 
ficient light, for miners can work where there is scarcely 
oxygen enough to sustain a small.flame. By the same 
