CORK-CUTTING. The bark, after being cut into square pieces or sheets, is pressed, to remove its natural curvature and flatten it. If it is found that simple pressure has not flattened it sufficiently, it is heated on the convex side, and the contraction thus pro. duced straightens it. It is then cut into slips, and these slips into squares, according to the required size of the corks. These are rounded by the cork-cutter by means of a broad sharp knife; the cork is held in the left hand, and rested against a block of wood, and the knife pushed forward, and at the same time its edge is made to describe a cir cular curve by a skillful turn of the wrist. The knife requires continual sharpening; the workman has a board before him on which the knife is rubbed on each side after every cut.
Many attempts have been made to cut corks by machinery. A patent cork-cutting company etas established a few years since, but it failed. The chief difficulty in applying
machines to this purpose arises from the necessity of continually sharpening the knife or cutters, for it is a curious fact, that so soft a substance as cork blunts the tools used in cutting it far more rapidly than do the hardest or toughest of metals. A cork-cutter's knife requires sharpening every second, while the tool that is used for planing, turning, or boring steel will work continously for hours without sharpening. In most of the machines, the corks, after being cut into squares of the required length, arc made to revolve on grasping spindles; and cutters of various forms, such as revolving cutter wheels, hollow cones with internal cutters, reciprocating blades, toothed cutters, etc., are brought to bear upon the revolving cork.