But to return to the stamping machines.
Some usually set up four
machines of this kind in one place, that is to say, two above and the same
number below. By this plan it is necessary that the current which has been
diverted should fall down from a greater height upon the upper waterÂ
wheels, because these turn axles whose cams raise heavier stamps. The
stamp-stems of the upper machines should be nearly twice as long as the stems
of the lower ones, because all the mortar-boxes are placed on the same level.
These stamps have their tappets near their upper ends, not as in the case of
the lower stamps, which are placed just above the bottom. The water flowing
down from the two upper water-wheels is caught in two broad races, from
which it falls on to the two lower water-wheels. Since all these machines
have the stamps very close together, the stems should be somewhat cut away,
to prevent the iron shoes from rubbing each other at the point where they are
set into the stems. Where so many machines cannot be constructed, by
reason of the narrowness of the valley, the mountain is excavated and
levelled in two places, one of which is higher than the other, and in this case
two machines are constructed and generally placed in one building. A
broad race receives in the same way the water which flows down from the
upper water-wheel, and similarly lets it fall on the lower water-wheel. The
mortar-boxes are not then placed on one level, but each on the level which
is appropriate to its own machine, and for this reason, two workmen are then
required to throw ore into the mortar-boxes. When no stream can be
diverted which will fall from a higher place upon the top of the water-wheel,
one is diverted which will turn the foot of the wheel; a great quantity of
water from the stream is collected in one pool capable of holding it, and
from this place, when the gates are raised, the water is discharged against
the wheel which turns in the race. The buckets of a water-wheel of this
kind are deeper and bent back, projecting upward; those of the former
are shallower and bent forward, inclining downward.
machines of this kind in one place, that is to say, two above and the same
number below. By this plan it is necessary that the current which has been
diverted should fall down from a greater height upon the upper waterÂ
wheels, because these turn axles whose cams raise heavier stamps. The
stamp-stems of the upper machines should be nearly twice as long as the stems
of the lower ones, because all the mortar-boxes are placed on the same level.
These stamps have their tappets near their upper ends, not as in the case of
the lower stamps, which are placed just above the bottom. The water flowing
down from the two upper water-wheels is caught in two broad races, from
which it falls on to the two lower water-wheels. Since all these machines
have the stamps very close together, the stems should be somewhat cut away,
to prevent the iron shoes from rubbing each other at the point where they are
set into the stems. Where so many machines cannot be constructed, by
reason of the narrowness of the valley, the mountain is excavated and
levelled in two places, one of which is higher than the other, and in this case
two machines are constructed and generally placed in one building. A
broad race receives in the same way the water which flows down from the
upper water-wheel, and similarly lets it fall on the lower water-wheel. The
mortar-boxes are not then placed on one level, but each on the level which
is appropriate to its own machine, and for this reason, two workmen are then
required to throw ore into the mortar-boxes. When no stream can be
diverted which will fall from a higher place upon the top of the water-wheel,
one is diverted which will turn the foot of the wheel; a great quantity of
water from the stream is collected in one pool capable of holding it, and
from this place, when the gates are raised, the water is discharged against
the wheel which turns in the race. The buckets of a water-wheel of this
kind are deeper and bent back, projecting upward; those of the former
are shallower and bent forward, inclining downward.
Further, in the Julian and Rhaetian Alps15 and in the Carpathian
Mountains, gold or even silver ore is now put under stamps, which are
sometimes placed more than twenty in a row, and crushed wet in a long mortarÂ
box. The mortar has two plates full of holes through which the ore, after
being crushed, flows out with the water into the transverse launder placed
underneath, and from there it is carried down by two spouts into the heads of
the canvas strakes. Each head is made of a thick broad plank, which can be
raised and set upright, and to which on each side are fixed pieces projecting
upward. In this plank there are many cup-like depressions equal in size and
similar in shape, in each of which an egg could be placed. Right down in
these depressions are small crevices which can retain the concentrates of gold
or silver, and when the hollows are nearly filled with these materials, the
plank is raised on one side so that the concentrates will fall into a large bowl.
The cup-like depressions are washed out by dashing them with water. These
Mountains, gold or even silver ore is now put under stamps, which are
sometimes placed more than twenty in a row, and crushed wet in a long mortarÂ
box. The mortar has two plates full of holes through which the ore, after
being crushed, flows out with the water into the transverse launder placed
underneath, and from there it is carried down by two spouts into the heads of
the canvas strakes. Each head is made of a thick broad plank, which can be
raised and set upright, and to which on each side are fixed pieces projecting
upward. In this plank there are many cup-like depressions equal in size and
similar in shape, in each of which an egg could be placed. Right down in
these depressions are small crevices which can retain the concentrates of gold
or silver, and when the hollows are nearly filled with these materials, the
plank is raised on one side so that the concentrates will fall into a large bowl.
The cup-like depressions are washed out by dashing them with water. These