The paper process of stereotyping was invented some years ago on the continent, but has been since perfected in the Times office, where it was adopted for duplicating newspaper forms. See TIMES. A uniform sheet of soft and damp matter is formed by gumming together, first, a sheet of thin yet very tough tissue paper; second, a sheet of loose and bibulous -white ,paper; and third, a sheet of fine-grained and tough brown paper. The smooth and white side of the sheet, still soft and moist, is placed on the types. Both are then put in a press. A roller passes under the form, and presses it up against the paper, so as to receive the impression of the types and convert it into a mold. The dents made by the types rise on the outside of the paper, so that any spot where the paper has not sunk into the spaces between the types is at once detected. Such spots generally occur, and are removed by the paper being driven in between the types by blows of a hard brush. The dents made by the types, we have said, are repre sented by elevations on the outside of the sheet, and the interstices are represented by corresponding hollows. The latter are filled up at this stage by a thin coating of stucco laid on by a.brusli. The mold is then carefully removal, dried, and placed in a shallow box of metal placed upright. The smooth or stucco side of the mold is pushed against the back of the box. The lid is then closed very tightly, leaving only an opening at the top. Through this opening molten metal is poured, and a plate is thus formed,, one side of which, of course, is a cast from the mold. It contains elevations at. places where there are wide spaces between the types, and these it is necessary to remove with the chisel. In other respects the plate is an exact copy of the form. The great advantage of this mode of stereotyping is its rapidity. Plates from stucco could scarcely be pro duced and ready for press in less than six hours; plates from paper can be produced and laid on the machine in less than one hour. Indeed, in the Times office, where the pro cess has been carried to great perfection, the plates are now produced in seven minutes.
By the paper process, plates are produced every morning for the London newspapers and others of which vast impressions are required. The forms of types themselves are no longer used, a number of plates being produced corresponding to the number of machines employed (see TrrEs), and all the copies of the paper are printed from them. A very great saving in the cost of types is thus effected. It was necessary to renew the fount every few months in the Times office, when that paper was printed in the usual way. Since the introduction of the new process, the expense of the production of that great newspaper has been to a considerable degree kept in check. The types last as many years as they did months when printed from. To accommodate printing machines -on which the forms need to be fixed in a cylinder, the paper molds are placed in pans .or boxes which are of the required shape. The molds are then bent with their backs -outward, and the molten metal is poured between the concave mold and convex lid. The plates are generally cast in four segments, which screwed together form a cylinder. They are adjusted to the printing press by a planing machine, which cuts their inner surface to the exact convexity of the cylinder. To this duplication there is of course no limit ; sets of plates can be oroduced to any required number As copies of old news papers are not wanted, the plates are melted down as soon as the operations of the day are over. Even when books are printed from movable types, it may serve a good pur pose to take paper molds from them before distribution ; for the molds, on being dried, •can be laid aside and be afterward employed for fabricating plates should a new impres sion be wanted. The author of a book, for example, could at a most insignificant addi tion to the expense of typography, possess himself of a set of paper molds of his work, to be used if necessary at some future period, in order to save the composition for a new edition.