Type-founding
Typography means writing by types. Movable types were used for printing in China and Japan long before the art was practised in Europe; blocks were used there as far back as the sixth century, but it was not till the tenth century that books were produced. The Chinese employed movable types of clay about the eleventh century, and in the fifteenth century the Coreans invented types of copper. The book trade was established in Europe about the thirteenth century, and it was about the year 1457 that Faust and Schoeffer printed with movable wooden types. Some think that the earliest types were cast in sand, and followed later by plaster moulds; but whatever process of casting was then employed, their form corresponds with those now in use--lead, iron, copper, tin, steel, and brass being all employed in their production at that time.
The earliest printers cast their own types, but the modern type-founder has usurped that part of the business. To make a type in the ordinary way, the letter is first cut on the end of a soft steel punch and then hardened, after which the impression is obtained on a piece of polished copper. This impression is the matrix, on which the face of the type is cast after it has been enclosed within a metal mould. The metal is poured into the mould by the workman, who gives it a quick jerk, after it has been filled, to solidify it. The above is the hand-mould method practised until about 1838, when a type-casting machine was invented by David Bruce of New York, followed by many others of a similar description, most of which kept the metal fluid by gas-jets, and forced it into the moulds with a pump, making an average of 100 types per minute. Johnson's English patent consists of a furnace covered by a shallow pot of fused metal, in which the pump and mould are placed, opposite its nozzle. After adjustment the metal is injected and solidifies, forming a type, with jet or gate attached. This letter is thrust out, and the mould closes for another cast, all of which takes place at one revolution of the axis. As they are thus cast and delivered, the letters are guided to the dressing-machine, and by a subsequent series of automatically performed operations they are finally delivered ready for the printer. See TYPE-METAL; STEREO-TYPE.