Print/ing

The art of producing impre ions paper. It is divided into the printing of books and newspapers from movable type, and from stereotype or electrotype plates. Printing was known to the Chinese as early as the sixth cen¬ tury, but their system was that of printing from engraved blocks. The invention of movable types is claimed by the Dutch in favor of Coster, 1420; and by the Germans on behalf of Guten¬ berg, 1440. Printing was introduced into Eng¬ land by Caxton in 1477. Wooden types were first used, but those made of type metal are now general. The first apparatus used for taking impre ions from types and blocks was in form of a screw-pre . This rude contrivance was soon replaced by a wooden lever-pre , which in turn gave way to the hand-pre made of iron, and this to the steam-pre . Books are printed either on single-cylinder machines, which print one side of a sheet of paper pa ing it over a form of type or plates, or double-cylinder or perfecting machines, which print both sides of the sheet while it pa es through the machine. In both cases ink \q. is supplied by a self-inking apparatus, consisting of slabs and several soft composition rollers. Newspapers and periodicals are printed on rotary or web-printing machines, which take an im¬ pre ion from curved stereotype plates fixed on rotating cylinder, the paper being run into machine from huge reels. These machines pro¬ duce from 12,000 to 24,000 printed sheets hour. The Walter pre , the Victory, the Hoe, and the Mar in on i are most in use, and usually have folding-machines attached, which deliver the sheets folded. For some periodicals, not only the body of the magazine but the cover printed on the same machine, and the magazine folded and inserted inside the cover. prize in — priein, to saw.] A piece of wood, metal, gla , etc., the ends of which are parallel, and equal in size and shape, and the sides parallelograms. Prisms of different forms often named from the figure of their bases, triangular, hexagonal, etc.—In optics, a three sided piece of gla with two equal and parallel triangular ends, used for separating the colors in a ray of light, and in refraction, etc. (See Spec¬ trum.} cause cut and trimmed.] An ornamental P.uropean shrub, much used in hedges. ship, usually consisting of a screw placed in the stern, and made to revolve under the water by plum, much used in cookery. The best prunes come from France, where several kinds of plums are raised for making prunes. Great quantities are also exported from Bosnia and Servia. northern Europe and America. Its color in summer is a pale-brown or ash, with wings and under-plumage white. In winter its plumage changes in color to a pure white. the so called from its short, thick, swollen beak and the rounded belly. It is also known by the names of bottle-nose, cock andy, coulter neb, mormon, pope, and sea-parrot. a colt.] One of the mechanical powers, consist¬ ing of a wheel called the sheave, movable about the per an axis, and having a groove cut in its circum¬ ference, over which a cord or rope pa es. The rope is attached at one end to a fixed point, and the force acting on the free end of the rope is doubled, but the load is only moved through half the space traversed by the rope. Pulleys are used either singly to change the direction of the power applied, or in various forms of com¬ bin at i on to raise heavy weights. volcanoes. It is a spongy lava, so light that it well or reservoir of water, and the upper end communicates with a wider pipe, called the bar¬ rel which has a lid on the top and a spout on ing the pump the air below the piston is exhaus¬ ted, and water is forced into the vacuum and through the lower valve by atmospheric pre ure. On the descent of the piston the water above the lower valve, closing that valve by its weight, pa es through the piston, and is then lifted to the level of the discharging tube or spout. (See Air-pump and Force-pump.)