A machine for speedily producing a fac-simile copy of any manuscript recently written. The method is to place over the letter a sheet of thin damp paper, and subject them both to the action of the press, by which means a portion of the ink is transferred from the manuscript to the damp paper. When letters are intended to be copied by this means, it is usual either to make use of a kind of ink expressly prepared for the purpose, or to add a portion of sugar to the common writing ink. The presses are variously constructed; but the screw press, new so common in merchants' counting-houses, is the invention of the celebrated James Watt, who obtained a patent for it about forty years ago. The annexed figure represents an improvement upon this machine, invented by Mr. Ritchie, of Edinburgh, a the bed of the press; b the platten; c c handles which revolve on the screw d, and are used to draw down the platten on the paper, etc. placed underneath; e is a square piece of steel in which the screw works; the square piece slides in a hole of a similar figure on the head of the press, (as shown by the dotted lines at f), and on the top of it is a small cam g, operated upon by the lever h.
The ordinary pressure is given, as usual, by the screw; and the cam being subsequently brought down, increases the force almost to infinity through a very small space, and, consequently, by such a press, a person exerting only the usual force can print effectually a larger surface. The other arrangements will be evident upon an inspection of the drawing.
A very simple, and, at the same time, effectual, copying machine may be made as follows: Take a roller of beech, or any hard wood, about 18 inches long, and 1 inch in diameter, and having cut a longitudinal slit therein nearly the whole length, insert in it and fasten very neatly with glue a slip of strong cloth, about 14 inches wide, and 18 inches long; the remaining part of the roller will serve as a handle, and may be cut with several faces to obtain a firmer hold. To use this copying press, lay the sheet of paper on which the letter is written upon the strip of cloth; on that place the thin copying paper, and upon these lay a thick baize, or horse-hair pad; then roll the whole round the roller, and grasping that part where the cloth is with the left hand, turn the roller round with the right, gradually increasing the grasp with the left; the pressure becomes very great, and quite sufficient to transfer the letter to the copying paper.