worked, though they were not deficient in silver. The fifth cause are the
fierce and murderous demons, for if they cannot be expelled, no one escapes
from them. The sixth cause is that the underpinnings become loosened
and collapse, and a fall of the mountain usually follows ; the underpinnings
are then only restored when the vein is very rich in metal. The seventh
cause is military operations. Shafts and tunnels should not be re-opened
unless we are quite certain of the reasons why the miners have deserted them,
because we ought not to believe that our ancestors were so indolent and
spiritless as to desert mines which could have been carried on with profit.
Indeed, in our own days, not a few miners, persuaded by old women's tales,
have re-opened deserted shafts and lost their time and trouble. Therefore,
to prevent future generations from being led to act in such a way, it is
advisable to set down in writing the reason why the digging of each shaft or
tunnel has been abandoned, just as it is agreed was once done at Freiberg,
when the shafts were deserted on account of the great inrush of water.
END OF BOOK VI.
