In a stout A framing were mounted two horizontal rollers or cylinders, which were made to revolve in opposite directions by means of pinions at one of their extremities gearing into each other. The lower roller was solid and turned concentrically upon its axis; over this roller the skin in its wet state was spread out across its breadth, with its even side next to the roller, the uneven or flesh side being uppermost. To give an uniform pressure to the uneven side of the skin, a species of flexibility was conferred to the upper roller by compounding it of a series of circular metallic plates, like a roll of penny pieces, but which were about half an inch in thickness, and three inches in diameter; each plate had two holes, one in the centre, through which passed a fixed axis, smaller than the hole, in order that the plates might have a certain degree of play or eccentricity of motion; the other hole was about midway between the centre and the circumference, through which a rod passed freely, the extremities of which were so fixed to flanges at the extremity of the roller as to perform a planetary motion round the common centre of the plates; and as the rod passed through all the circular plates, they were all carried round with it, while the centre of motion of each individual plate, owing to the play given to them, were constantly being changed in proportion to the thickness of that part of the skin pressed against it, by the revolution of the lower inflexible roller.

As the skin emerged from the bite between the rollers, it came in contact with the straight edge of a very sharp knife, to which a constant sawing-like motion was communicated by the revolution of a crank. The circular plates, which were turned with great truth, were not pressed fast laterally, but kept slack and well oiled, their sides sliding freely against one another, so that each individual plate pressed simply by its own gravity, in order that however varied the thickness of the skin, the pressure should be uniform over the whole surface.

By this arrrangement it will be observed, that the upper portion of the skin is the uneven one, and that the lower portion is the perfect skin, smooth, and uniform in all its parts. As a curiosity, and to show the capability of the machine, 6heep-skins were sometimes split into three parts of equal area; the outside one being applicable to the preparation of several kinds of leather, the middle to the making of parchment, while that on the flesh side, from its inequality of thickness, and want of firmness, was only applicable to the making of glue.