BLOCK PRINTING

still practiced in China and practiced in Europe before the invention of type. It was employed in China 50 B.C. The matter to be printed on a whole page was first inscribed on a very thin paper, and might include illustrations. The paper was then pasted, face down, on a block of wood. An engraver then carved out the blocks so that the printing was brought out in relief. The raised surfaces were then inked, a piece of paper laid carefully over them and a brush was applied to the back of the paper. In 925 A.D. the Imperial College of Peking had all the Chinese cla ics printed by the method. It is still in use in provincial parts of China, not only because of the cheapne of labor, but because Chinese characters are especially adapted to this method, each word requiring a character of its own. In Europe the initial letters of manuscripts were first made on blocks, and gradually block printing came into practice, the whole page being carved on one block. But when individual type was cast, it was quickly abandoned. BLOCK SIGNAL SYSTEM. A method of railroad traffic regulation, whereby the operator of a train is warned by some form of signal when his train approaches closer than a predetermined distance to the preceding train. In some systems, a device placed close to the track adjacent to the signals, engages with a trip on the locomotive, automatically shutting off the power and applying the brakes, thus bringing the train to a stop, when it attempts to pa a signal set at danger. The mechanism is as follows:—The track is divided into sections called blocks, which on long, straight stretches may be three or four miles in extent, while on curved mountainous sections they are but several hundred yards long. Where traffic is heavy the blocks are short, whereas light traffic permits of longer blocks. Electric, or combined electric and pneumatically operated signals are placed at the dividing lines between blocks. These signals are controlled through relays by devices placed on the track at points one or two blocks distant. When the train pa es one of these track instruments the wheels either complete an electric circuit, or depre levers which do so, thereby simultaneously setting the distant signal at clear, and the adjacent signal at danger. In most systems, when the signal two blocks back is set at clear, that one block back indicates caution, and the signal at the entrance to the block occupied by the train, danger. Thus greatly reduced speed should be used, after pa ing a signal set at caution, while danger should effect a complete stop. On single track roads, over which trains are operated in both directions, additional interlocking devices are employed, which prevent one train’s entering a block in which another is running in the opposite direction. g E.), formerly republican capital, now provincial capital, Orange Free State (q.v.), 9. Africa; situated on a plain; elevation, 4518 ft.; well-built, large gardens; healthy climate; Grey Univ. Coll.; seat of Supreme Court of S. Africa; Military Coll.; occupied by Lord Roberts, March, 1900 and annexed May May 28. Pop. 1921, 38,865 (white 19,333) Loir-et-Cher, France, on Loire; castle of great hist. interest (XIII-X VI. cent’s); favorite residence of Fr. kings; Gothic cathedral; wine, shoes. Blois was one of the important headquarters of the American Expeditionary Force during the World War. Pop. 24,000.