1the back one of which is round and a digit in diameter, and in this is
engaged
the first link of the chain as I have stated; the hole at the front end is two
digits and a half long and a digit and a half wide. This end of each rod
is made three digits wide, while for the rest of its length it is only two digits,
and at the back it is two and a half digits. Into the front hole of each rod is
driven an iron bar, which is three feet and two palms long, two digits wide
and one thick; in the end of this bar are five small square holes, two-thirds
of a digit square; each hole is distant from the other half a digit, the first
being at a distance of about a digit from the end. Into one of these holes the
refiner drives an iron pin; if he should desire to make the furnace narrower,
then he drives it into the last hole; if he should desire to widen it, then into
the first hole; if he should desire to contract it moderately, then into one
of the middle holes. For the same reason, therefore, the hook is sometimes
inserted into the last link of the chain, and sometimes into the third or the
second. The furnace is widened when many cakes are put into it, and con
tracted when there are but few, but to put in more than five is neither usual
nor possible; indeed, it is because of thin cakes that the walls are contracted.
The bar has a hump, which projects a digit on each side at the back, of the
same width and thickness as itself. These humps project, lest the bar should
slip through the hole of the right-hand rod, in which it remains fixed when
it, together with the rods, is not pressing upon the furnace walls.
the first link of the chain as I have stated; the hole at the front end is two
digits and a half long and a digit and a half wide. This end of each rod
is made three digits wide, while for the rest of its length it is only two digits,
and at the back it is two and a half digits. Into the front hole of each rod is
driven an iron bar, which is three feet and two palms long, two digits wide
and one thick; in the end of this bar are five small square holes, two-thirds
of a digit square; each hole is distant from the other half a digit, the first
being at a distance of about a digit from the end. Into one of these holes the
refiner drives an iron pin; if he should desire to make the furnace narrower,
then he drives it into the last hole; if he should desire to widen it, then into
the first hole; if he should desire to contract it moderately, then into one
of the middle holes. For the same reason, therefore, the hook is sometimes
inserted into the last link of the chain, and sometimes into the third or the
second. The furnace is widened when many cakes are put into it, and con
tracted when there are but few, but to put in more than five is neither usual
nor possible; indeed, it is because of thin cakes that the walls are contracted.
The bar has a hump, which projects a digit on each side at the back, of the
same width and thickness as itself. These humps project, lest the bar should
slip through the hole of the right-hand rod, in which it remains fixed when
it, together with the rods, is not pressing upon the furnace walls.
There are three panels to the furnace—two at the sides, one in front
and another at the back. Those which are at the sides are three feet
and as many palms and two digits long, and two feet high; the front one is
two feet and a palm and three digits long, and, like the side ones, two feet
high. Each consists of iron bars, of feet, and of iron plates. Those which are
at the side have seven bars, the lower and upper of which are of the same
length as the panels; the former holds up the upright bars; the latter is
placed upon them; the uprights are five in number, and have the same height
as the panels; the middle ones are inserted into holes in the upper and lower
bars; the outer ones are made of one and the same bar as the lower and
upper ones. They are two digits wide and one thick. The front panel has
five bars; the lower one holds similar uprights, but there are three of them
only; the upper bar is placed on them. Each of these panels has two feet
fixed at each end of the lower bar, and these are two palms long, one wide,
and a digit thick. The iron plates are fastened to the inner side of the bars
with iron wire, and they are covered with lute, so that they may last longer
and may be uninjured by the fire. There are, besides, iron blocks three palms
long, one wide, and a digit and a half thick; the upper surface of these is
somewhat hollowed out, so that the cakes may stand in them; these iron
blocks are dipped into a vessel in which there is clay mixed with water, and
they are used only for placing under the cakes of copper and lead alloy made
in the furnaces. There is more silver in these than in those which are
made of liquation thorns, or furnace accretions, or re-melted “slags.” Two
iron blocks are placed under each cake, in order that, by raising it up, the fire
may bring more force to bear upon it; the one is put on the right bed-plate,
and another at the back. Those which are at the sides are three feet
and as many palms and two digits long, and two feet high; the front one is
two feet and a palm and three digits long, and, like the side ones, two feet
high. Each consists of iron bars, of feet, and of iron plates. Those which are
at the side have seven bars, the lower and upper of which are of the same
length as the panels; the former holds up the upright bars; the latter is
placed upon them; the uprights are five in number, and have the same height
as the panels; the middle ones are inserted into holes in the upper and lower
bars; the outer ones are made of one and the same bar as the lower and
upper ones. They are two digits wide and one thick. The front panel has
five bars; the lower one holds similar uprights, but there are three of them
only; the upper bar is placed on them. Each of these panels has two feet
fixed at each end of the lower bar, and these are two palms long, one wide,
and a digit thick. The iron plates are fastened to the inner side of the bars
with iron wire, and they are covered with lute, so that they may last longer
and may be uninjured by the fire. There are, besides, iron blocks three palms
long, one wide, and a digit and a half thick; the upper surface of these is
somewhat hollowed out, so that the cakes may stand in them; these iron
blocks are dipped into a vessel in which there is clay mixed with water, and
they are used only for placing under the cakes of copper and lead alloy made
in the furnaces. There is more silver in these than in those which are
made of liquation thorns, or furnace accretions, or re-melted “slags.” Two
iron blocks are placed under each cake, in order that, by raising it up, the fire
may bring more force to bear upon it; the one is put on the right bed-plate,