1hearth,
for it does not project beyond the wall.
The hide of the bellows is
fixed to the bellows-boards with its own peculiar kind of iron nails. It joins
both bellows-boards to the head, and over it there are cross strips of
hide fixed to the bellows-boards with broad-headed nails, and similarly
fixed to the head. The middle board of the bellows rests on an iron bar,
to which it is fastened with iron nails clinched on both ends, so that it cannot
move; the iron bar is fixed between two upright posts, through which it
penetrates. Higher up on these upright posts there is a wooden axle, with
iron journals which revolve in the holes in the posts. In the middle of
this axle there is mortised a lever, fixed with iron nails to prevent it from
flying out; the lever is five and a half feet long, and its posterior end is
engaged in the iron ring of an iron rod which reaches to the “tail” of the
lowest bellows-board, and there engages another similar ring. And so when
the workman pulls down the lever, the lower part of the bellows is raised and
drives the wind into the nozzle; then the wind, penetrating through the hole
in the middle bellows-board, which is called the air-hole, lifts up the upper
part of the bellows, upon whose upper board is a piece of lead, heavy enough
to press down that part of the bellows again, and this being pressed down
blows a blast through the nozzle. This is the principle of the double bellows,
which is peculiar to the iron hoop where are placed the triangular crucibles in
which copper ore is smelted and copper is melted.
fixed to the bellows-boards with its own peculiar kind of iron nails. It joins
both bellows-boards to the head, and over it there are cross strips of
hide fixed to the bellows-boards with broad-headed nails, and similarly
fixed to the head. The middle board of the bellows rests on an iron bar,
to which it is fastened with iron nails clinched on both ends, so that it cannot
move; the iron bar is fixed between two upright posts, through which it
penetrates. Higher up on these upright posts there is a wooden axle, with
iron journals which revolve in the holes in the posts. In the middle of
this axle there is mortised a lever, fixed with iron nails to prevent it from
flying out; the lever is five and a half feet long, and its posterior end is
engaged in the iron ring of an iron rod which reaches to the “tail” of the
lowest bellows-board, and there engages another similar ring. And so when
the workman pulls down the lever, the lower part of the bellows is raised and
drives the wind into the nozzle; then the wind, penetrating through the hole
in the middle bellows-board, which is called the air-hole, lifts up the upper
part of the bellows, upon whose upper board is a piece of lead, heavy enough
to press down that part of the bellows again, and this being pressed down
blows a blast through the nozzle. This is the principle of the double bellows,
which is peculiar to the iron hoop where are placed the triangular crucibles in
which copper ore is smelted and copper is melted.
I have spoken of the furnaces and the iron hoop; I will now speak of
the muffles and the crucibles. The muffle is made of clay, in the shape
of an inverted gutter tile; it covers the scorifiers, lest coal dust fall into
them and interfere with the assay. It is a palm and a half broad, and the
height, which corresponds with the mouth of the furnace, is generally a palm,
the muffles and the crucibles. The muffle is made of clay, in the shape
of an inverted gutter tile; it covers the scorifiers, lest coal dust fall into
them and interfere with the assay. It is a palm and a half broad, and the
height, which corresponds with the mouth of the furnace, is generally a palm,