Archive image from page 264 of De re metallica (1950). De re metallica deremetallica50agri Year: 1950 BOOK VII. 227 hearth, for it does not project beyond the wall. The hide of the bellows is fixed to the bellows-boards with its own pecuhar kind of iron nails. It jf)ins both bellows-boards to the head, and over it there are cross strijjs 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 cUnched on both ends, so that it cannot move ; the iron bar is fixed be
Archive image from page 264 of De re metallica (1950). De re metallica deremetallica50agri Year: 1950 BOOK VII. 227 hearth, for it does not project beyond the wall. The hide of the bellows is fixed to the bellows-boards with its own pecuhar kind of iron nails. It jf)ins both bellows-boards to the head, and over it there are cross strijjs 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 cUnched 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. A—Iron hoop. B—Double bellows. C—Its nozzle. D—Lever. 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
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