1method of grinding requires the millstone to be
now raised and now
lowered, the timber in whose socket the iron of the pinion axle revolves, rests
upon two beams, which can be raised and lowered.
lowered, the timber in whose socket the iron of the pinion axle revolves, rests
upon two beams, which can be raised and lowered.
There are three mills in use in milling gold ores, especially for quartz11
which is not lacking in metal. They are not all turned by water-power,
but some by the strength of men, and two of them even by the power
of beasts of burden. The first revolving one differs from the next only
in its driving wheel, which is closed in and turned by men treading it, or by
horses, which are placed inside, or by asses, or even by strong goats; the
eyes of these beasts are covered by linen bands. The second mill, both
when pushed and turned round, differs from the two above by having an
upright axle in the place of the horizontal one; this axle has at its lower end
a disc, which two workmen turn by treading back its cleats with their feet,
though frequently one man sustains all the labour; or sometimes there
projects from the axle a pole which is turned by a horse or an ass, for which
reason it is called an asinaria. The toothed drum which is at the upper end
of the axle turns the drum which is made of rundles, and together with it the
millstone.
which is not lacking in metal. They are not all turned by water-power,
but some by the strength of men, and two of them even by the power
of beasts of burden. The first revolving one differs from the next only
in its driving wheel, which is closed in and turned by men treading it, or by
horses, which are placed inside, or by asses, or even by strong goats; the
eyes of these beasts are covered by linen bands. The second mill, both
when pushed and turned round, differs from the two above by having an
upright axle in the place of the horizontal one; this axle has at its lower end
a disc, which two workmen turn by treading back its cleats with their feet,
though frequently one man sustains all the labour; or sometimes there
projects from the axle a pole which is turned by a horse or an ass, for which
reason it is called an asinaria. The toothed drum which is at the upper end
of the axle turns the drum which is made of rundles, and together with it the
millstone.
The third mill is turned round and round, and not pushed by hand; but
between this and the others there is a great distinction, for the lower
millstone is so shaped at the top that it can hold within it the upper mill
stone, which revolves around an iron axle; this axle is fastened in the
centre of the lower stone and passes through the upper stone. A workman,
by grasping in his hand an upright iron bar placed in the upper millstone,
moves it round. The middle of the upper millstone is bored through, and
the ore, being thrown into this opening, falls down upon the lower millstone
and is there ground to powder, which gradually runs out through its opening;
it is washed by various methods before it is mixed with quicksilver,
which I will explain presently.
between this and the others there is a great distinction, for the lower
millstone is so shaped at the top that it can hold within it the upper mill
stone, which revolves around an iron axle; this axle is fastened in the
centre of the lower stone and passes through the upper stone. A workman,
by grasping in his hand an upright iron bar placed in the upper millstone,
moves it round. The middle of the upper millstone is bored through, and
the ore, being thrown into this opening, falls down upon the lower millstone
and is there ground to powder, which gradually runs out through its opening;
it is washed by various methods before it is mixed with quicksilver,
which I will explain presently.
Some people build a machine which at one and the same time can crush,
grind, cleanse, and wash the gold ore, and mix the gold with quicksilver.
This machine has one water-wheel, which is turned by a stream striking its
buckets; the main axle on one side of the water-wheel has long cams, which
raise the stamps that crush the dry ore. Then the crushed ore is thrown
into the hopper of the upper millstone, and gradually falling through the
opening, is ground to powder. The lower millstone is square, but has a round
depression in which the round, upper millstone turns, and it has an outlet
from which the powder falls into the first tub. A vertical iron axle is dove
tailed into a cross-piece, which is in turn fixed into the upper millstone;
the upper pinion of this axle is held in a bearing fixed in a beam; the drum
of the vertical axle is made of rundles, and is turned by the toothed drum
on the main axle, and thus turns the millstone. The powder falls continually
into the first tub, together with water, and from there runs into a second tub
which is set lower down, and out of the second into a third, which is the
lowest; from the third, it generally flows into a small trough hewn out of a
grind, cleanse, and wash the gold ore, and mix the gold with quicksilver.
This machine has one water-wheel, which is turned by a stream striking its
buckets; the main axle on one side of the water-wheel has long cams, which
raise the stamps that crush the dry ore. Then the crushed ore is thrown
into the hopper of the upper millstone, and gradually falling through the
opening, is ground to powder. The lower millstone is square, but has a round
depression in which the round, upper millstone turns, and it has an outlet
from which the powder falls into the first tub. A vertical iron axle is dove
tailed into a cross-piece, which is in turn fixed into the upper millstone;
the upper pinion of this axle is held in a bearing fixed in a beam; the drum
of the vertical axle is made of rundles, and is turned by the toothed drum
on the main axle, and thus turns the millstone. The powder falls continually
into the first tub, together with water, and from there runs into a second tub
which is set lower down, and out of the second into a third, which is the
lowest; from the third, it generally flows into a small trough hewn out of a