BOOK XI.
503
rotates with it; therefore, when the axle revolves, the little axle and
the bronze tube in their turn raise the tooth and the stamp. When the
little iron axle and the bronze pipe have been taken out of the arms, the tooth
of the stamps is not raised, and other stamps may be raised without this one.
Further on, a drum with spindles fixed around the axle of a water-wheel
moves the axle of a toothed drum, which depresses the sweeps of the bellows
in the adjacent fourth part of the building; but it turns in the contrary
direction; for the axis of the drum which raises the stamps turns toward
the north, while that one, which depresses the sweeps of the bellows turns
toward the south.
Those cakes which are too thick to be rapidly broken by blows from
the iron-shod stamp, such as are generally those which have settled in the
bottom of the crucible,9 are carried into the first part of the building. They
are there heated in a furnace, which is twenty-eight feet distant from the
second long wall and twelve feet from the second transverse wall. The three
sides of this furnace are built of rectangular rocks, upon which bricks are laid ;
the back furnace wall is three feet and a palm high, and the rear of the side
walls is the same ; the side walls are sloping, and where the furnace is open in
front they are only two feet and three palms high; all the walls are a foot and
a palm thick. Upon these walls stand upright posts not less thick, in order
that they may bear the heavy weight placed upon them, and they are covered
with lute ; these posts support the sloping chimney and penetrate through
the roof. Moreover, not only the ribs of the chimney, but also the rafters,
are covered thickly with lute. The hearth of the furnace is six feet
long on each side, is sloping, and is paved with bricks. The cakes of copper
are placed in the furnace and heated in the following way. They are first of
all placed in the furnace in rows, with as many small stones the size of an egg
between, so that the heat of the fire can penetrate through the spaces between
them ; indeed, those cakes which are placed at the bottom of the crucible are
each raised upon half a brick for the same reason. But lest the last row,
which lies against the mouth of the furnace, should fall out, against the mouth
are placed iron plates, or the copper cakes which are the first taken from the
crucible when copper is made, and against them are laid exhausted liquation
cakes or rocks. Then charcoal is thrown on the cakes, and then live coals;
at first the cakes are heated by a gentle fire, and afterward more charcoal is
added to them until it is at times three-quarters of a foot deep. A fiercer fire
is certainly required to heat the hard cakes of copper than the fragile ones.
When the cakes have been sufficiently heated, which usually occurs within
the space of about two hours, the exhausted liquation cakes or the rocks
and the iron plate are removed from the mouth of the furnace. Then the
hot cakes are taken out row after row with a two-pronged rabble, such as the
one which is used by those who " dry " the exhausted liquation cakes.
Then the first cake is laid upon the exhausted liquation cakes, and beaten by
two workmen with hammers until it breaks ; the hotter the cakes are, the
•By this expression is apparently meant the " bottoms " produced in enriching copper,
as described on p. 510.
