The art of producing impressions on 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 century, 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 Gutenberg, 1440. Printing was introduced into England by Caxton in 1477. Wooden types were first used, but those made of type metal are now general. The first apparatus used for taking the impressions from types and blocks was in the form of a screw-press. This rude contrivance was soon replaced by a wooden lever-press, which in turn gave way to the hand-press made of iron, and this to the steam-press. Books are printed either on single-cylinder machines, which print one side of a sheet of paper by passing it over a form of type or plates, or on double-cylinder or perfecting machines, which print both sides of the sheet while it passes through the machine. In both cases ink (q. v.) 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 impression from curved stereotype plates fixed on a rotating cylinder, the paper being run into the machine from huge reels. These machines produce from 12,000 to 24,000 printed sheets per hour. The Walter press, the Victory, the Hoe, and the Marinoni 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 is printed on the same machine, and the magazine folded and inserted inside the cover.