850 PRINTING final correction, the matter is made up into pages ; and these, if the impressions are to be taken directly from the type, are imposed, or arranged upon a table of stone or iron, prop- erly separated by strips of wood or metal called furniture, in such a manner that when the printed sheet is folded they will follow each other in regular order. The form, as such a collection of pages is styled, is then wedged up in an iron frame called a chase, and is ready for the pressman. But frequently, and with us usually, the printing is from casts or plates, called stereotypes (Gr. artpeos, solid, and TVTTO^ type), from these type pages. The advantages of this are numerous, the chief of which are the ability to print according to demand, thus obviating the risk of loss by miscalculation of the market, the saving in wear of type and of the cost of resetting for new editions, and the facility for correcting errors in the plates discovered after the first or any subsequent impression. In the case of books like the Bible for which there is a constant demand, it was long ago found expedient to keep the type standing, at great expense from the quantity required, and work off a new edition only when the preceding one was nearly exhausted. But there was great risk that in repeatedly handling pages, each made up of thousands of separate pieces, some would be disarranged. To obviate this, Van der Meyer of Antwerp, early in the last century, formed pages into solid plates by soldering the type together at the bottom ; but as this did not release the type so that they could be used again, the pages, each near- ly an inch thick, for a large book formed an exceedingly costly pile. The art of casting solid plates in a mould from a page of type appears to have been first practised by Wil- liam Ged, a goldsmith of Edinburgh, about 1731. His moulds were taken in plaster of Paris, and he prepared plates of a Bible for the university of Cambridge ; but these were mutilated by the jealous printers, and were cast aside, and the process was abandoned for many years. In the mean while several other plans were tried. Firmin Didot of Paris had types made of a hard alloy, and the pages were impressed upon a sheet of soft lead, thus making a mould. Melted type metal was poured into a shallow tray, and just when it was at the point of solidifying, but still soft, the lead mould was laid upon its surface. In this state the two metals will not adhere, and thus a cast was obtained. This method was only partially successful ; it could not be em- ployed for large pages, and the plates were often imperfect. M. Cares of France (1786) made his mould by pressing half-melted lead on the form ; into this mould he poured melt- ed lead, and pressed it when cooling. Earl Stanhope, near the beginning of this century, reintroduced Ged's process with many improve- ments. One or more pages are locked up in a chase, and the surface of the type, having been oiled to prevent adhesion of the mould, is then covered with semi-fluid plaster of Paris ; a lit- tle salt is mixed with the plaster to facilitate setting, and is kept from spreading by a raised metal framework around the pages. When the plaster has set, it forms an almost perfect mould, which is carefully removed and trimmed with a sharp knife. The moisture in the moulds was formerly expelled by baking in an oven for about two hours, but this is now done in less than five minutes after they are placed in the casting pan, by first suspending it over the pot of melted metal and then allowing it to float on its surface ; thus the whole process of taking the mould and casting the plate can be accomplished in less than an hour. The composition used is softer than type metal, consisting of 91 parts of lead, 5 of antimony, and 4 of tin. Several moulds are placed side by side, face downward, on an iron floater in the pan ; the latter is If in. deep, and so con- structed that when submerged in the melted metal this flows in under the moulds, pressing them up against the cover, and forming plates about a quarter of an inch thick. The pan is then removed and gradually cooled with water, and the plates are freed from plaster and su- perfluous metal, and shaved on the back by a machine to a uniform thickness. They are then " picked " with suitable tools to free them from remaining bits of plaster or metal in the hollows of the letters or between them, and defective letters are made perfect, or cut out with a small chisel and replaced by type sol- dered in and cut off at the back. In this man- ner also errors subsequently discovered are cor- rected ; or if an error involves two or more lines, a "piece" is cast and soldered in, in place of the corresponding piece of the plate, removed by saw and chisel. Each plate is clamped to a wooden block of such thickness that both together are exactly type-high, and the blocks are imposed in a chase and the printing is performed as with type. When the edition of a sheet is printed, the plates are taken from the blocks, upon which an- other set is clamped. Stereotyping was in- troduced into the United States in 1813 by David Bruce of New York ; the first book pro- duced by it was a New Testament, in 1814. A more expeditious but less perfect method, called the papier mache process, was first used for books in France in 1848, and a few years later in New York. In 1861 it came into use in New York for daily newspapers of large circulation, and its application has since been greatly extended. The material for a matrix is formed by taking a damp sheet of thick un- sized paper, and laying over it a number of sheets of moistened tissue paper until the whole is as thick as stout pasteboard. The under side, lightly covered with pulverized French chalk, is laid upon the face of a page of type and beaten with a stiff brush so as to force the soft paper into all the interstices of the type. Other sheets of adhesive paper are added until a sufficient thickness is attained. The whole
