The stretching iron, [fig. 356.], is a flat plate of iron or copper, fully a fourth of an inch thick at top, and thinning off at bottom in a blunt edge, shaped like the arc of a circle of large diameter, having the angles a and b rounded, lest in working they should penetrate the leather. The top c is mounted with leather to prevent it from hurting the hands. A copper stretching knife is used for delicate skins. The workman holds this tool nearly perpendicular, and scrapes the thick places powerfully with his two hands, especially those where some tan or flesh remains. He thus equalizes the thickness of the skin, and renders it at the same time more dense and uniform in texture. This tool is of very general use in currying.
The round knife, [fig. 357.] and [358.] (lunette in French), is a circular knife from 10 to 12 inches in diameter, with a round 4 or 5 inch hole in its centre, for introducing the hands and working it. It is concave, as shown in the section [fig. 358.], presenting the form of a spherical zone. The concave part is that applied to the skin. Its edge is not perfectly straight; but is a little turned over on the side opposite to the skin, to prevent it from entering too far into the leather. The currier first slopes off with the head knife from the edges, a portion equal to what he afterwards removes with the round one. By this division the work is done sooner and more exactly. All the oiled or greased skins are dressed with the round knife.
The cleaner is a straight two-handled knife two inches broad, of which there are two kinds, a sharp-edged and a blunt one. [Fig. 359.]
The mace is made of wood, having a handle 30 inches long, with a cubical head or mallet; upon the two faces of which, parallel to the line of the handle, there are 4 pegs of hard wood turned of an egg-shape, and well polished, so as not to tear the moistened leather when it is strongly beat and softened with the mace.
