e of the world! At the present time
Botallack has progressed in that direction to a depth of 245 fathoms.
To those who find a difficulty in realising what depth that really is,
we would observe that it is equal to more than three and a half times
the height of St. Paul's Cathedral in London, nearly four times the
height of St. Rollox chimney in Glasgow, and considerably more than
twice the height, from the plain, of Arthur's Seat, near Edinburgh.

When the levels have been driven a considerable distance from the shaft,
the air naturally becomes bad from want of circulation. To remedy this
evil, holes, or short shafts, called "winzes," are sunk at intervals
from the upper to the lower levels. These winzes are dangerous traps
for the unwary or careless, extending frequently to a depth of ten or
fifteen fathoms, and being bridged across by one or two loose planks.
Ladders are fixed in many of them to facilitate progress through the
mine. When a miner drives the end of his level so far that the air will
not circulate, a new winze is usually sunk down to him from the level
above. The circulation is thus extended, and the levels progress
further and further right and left until they occupy miles of ground.
The levels and shafts of Botallack, if put together, would extend to not
less than forty miles, and the superficial space of ground, on and
beneath which the mine lies, is above 260 acres.

When the lode is rich, and extends upwards or downwards, it is cut away
from between levels, in a regular systematic manner, strong beams being
placed to support temporary platforms, on which the miners may stand and
work as they ascend. When they have cut all the lode away up to the
level above them, a false timber bottom is made to replace the rocky
bottom of the level which is being removed. Thus, in traversing the old
workings of a mine one suddenly comes to great caverns, very narrow, but
of such immense height above and depth below that the rays of your
candle cannot penetrate the darkness. In such places the thick short
beams that were used by the old miners are seen extending from side to
side of the empty space, disappearing in dim perspective. Woe betide
the man who stumbles off his narrow plank, or sets his foot on an
insecure beam in such places! Where such workings are in progress, the
positions of the miners appear singularly wild and insecure. The men
stand in the narrow chasm between the granite walls above eac