PIPE. 4G PIPE. soft, hot lead through n die. the diameter of which corresponds with the interior diameter of the piiK". The total pressure used is about 400 tons, distributed over a 14- or 16-inch cylinder. lilocL-liit jiipes are made in the same way as lead, except that they are eold-pressed. Most of the block-tin pipe is used in soda fountains, or to convey beer, or in chemical works. C'ast-Irox Pipes. The general process of cast- ing iron is described under ForxDiNG. It may be"said here that in some of the foundries the core is made by winding a spindle with a ma- chine-made hay rope. Over the rope two or three layers of clay are packed, successively, after which the clay is shaped in a lathe, then dried in an oven. This core shapes the interior of the pipe. For the exterior a pattern is pl.aced in a CDiiiparlmont known as a flask. Around the pattern tempered clay and sand are rammed to form a mold for the exterior of the pipe. The flask is then placed in an oven to dry the sand and clay, after which it is placed in a Bead Rin^ known as sewer pipe. A machine for the manu- facture of clay pipe was built at Ottweiler, Khenish Prussia, aboit 1858. Dhaix Tii.ks are commonly mere cylinders of baked clay, designedly porous, and without pro- vision for making joints. Sometimes, liowcver, a short length of semi-cylindrical baked clay is MOLII FOR CASTING IRON PIPE. vertical position, the core centred within it, and the s|>ace l)etween the core and the mold filled ■with molten iron, .fter the core is drawn and the pipe removed the latter is coated to prevent corrosion. The standard length of cast-iron pipe is 12 feet, and its diameter ranges from about 2 to fiO inches, with occasional larger sizes. The great thickness of shell, which of course increases with the diameter, makes very large pipe too heavy for use where ready means for handling it are not available. This is partly obviated by casting in shorter lengths. Clay. Earthenware, oh Terba-Cotta Pipe. Near the close of the eighteenth century the manufacture of drain tih' began to assume im- portance in England. Other forms of clay pipe followed soon after, and then came the vitrified clay or glazed stoneware pipe now commonly Four-VKiy Branch. Blow-off Branch, Sleeve. SOME OF TQE MOST COMMON SPECIAL CASTINGS FOR USE WITH CAST-IEON PIPE. laid over the abutting ends of the tiles. The standard vitrified clay or sewer pipe has sockets at one end for jointing, made of a little larger diameter than the pipe proper. Clay pipe is made by pressing or otherwise forcing the pre- pared clay (see Clay) through a die. in the case of drain tile, and then cutting it into short lengths; or it is pressed in a mold, consisting of an outer shell, to form the exterior, and a core for the interior, besides which there is a special mold for the socket. After the socket is formed its mold is removed and the straight portion of the pipe pushed through. To obtain a glaze, salt is jilaced in the fire holes of the kiln while the pipe is being baked. Upon being volatilized the salt combines with the silica in the clay. Drain tiles are quoted by manufacturers in diameters of 1V4 to 12 inches. and are made in lengths of 12 to 1.5 inches. Vitrified pipes run from 2 to 36 inches in diam- eter, and are generally 2, 2M>, or .3 feet long. There is a tendency to longer pipes, for the sake of reducing the number of joints. The lengths have to be restricted to 3 feet, to keep the pipes straight. Wood Pipes. Bored logs were used at Bos- ton, in the first ))ublie water-supply system in the I'nited States, in 1652, and at Bethlehem. Pa., in the pumping system of water-works built from 1754 to 1761. Iiost. if not all. these primi- tive wood pipes were simply logs with holes bored in their centres, and one end of each log tapered off to fit into the bore hole of the next log. Similar pipes are still used, but principally in the rural districts. Improvements have re- sulted in a style of pipe with a smooth circular interior and exterior, an asphalt-coated ircm or steel band wound tightly around the pipe to give it strength, and a coating of asphalt over lioth the bands ami wood for preserving the ex- terior from alternate dri-ing and wetting. The joints are made by boring out one end of each
