Bagshaw's patent earthen pipes are thus made :—Chlindrical plugs of wood, of the same diameter as the bore of the intended pipe, and of the same length, are coated with a sufficient thickness of clay, or plastic earth, which has been duly prepared in the manner practised in the potteries. To perfect the exterior form of the pipe, an external mould is to be employed, consisting of two semi cylindrical pieces, which are to be placed on each side of the intended pipe, when the edges are to be brought together by screwing them up, which will press out the superfluous clay from the mould ; the exterior mould being next removed, the pipe will be found completely formed upon the plug : in this state it is to be dried ; after which the plug may be easily withdrawn, and the pipes finished, by baking them in an oven. The pipes are to be connected together by inserting the smaller end of one into the larger end of another, and filling up the interstices between them with Roman or other soft fluid cement. Pipes produced in a similar manner, of which the material was • cement or imitation of skins, have likewise been brought into use.
Some years since Mr. Murdock took out a patent for the economical fabrica tion of pipes of real stone, the process combining the advantage of making solid cylinders at the same time. In forming a pipe or hollow cylinder of stone, instead of cutting out in useless scrape, or grinding to powder, the whole diameter of the bore, the patentee cuts out a core or solid cylinder, whose out side diameter is only about half an inch less than the inside diameter of the pipe. In like manner, when he intends to form • column or solid cylinder, or disc of stone, instead of breaking off, cutting, or chiseling away the super fluous parts of the stone, these parts are formed into a hollow cylinder, the core of which is the solid cylinder or disc required. Hence, if the stone is large enough to leave the outside parts of a proper thickness, these parts may be used as a pipe, and the core may either be used as a solid cylinder or column ; or, by a farther operation, it may be converted into apipe, and the cylinder cut out of it may again be converted into another pipe, winch process may be con tinued until the core cut out is too small to be useful. The following is the mode adopted by the patentee of accomplishing fixes the block of stone to be perforated in an upright position, and in the centre of the top of the block of stone, a step to receive the toe of a vertical spindle, which derives its motion from a pulley turning in plummer-blocks in a fixed frame above ; this axis is considerably longer than the pipe or column to be formed, having the faculty of Biding vertically through the aforesaid horizontal pulley, over which it Is suspended by a rope that passes round a vertical pulley, and thence is connected to a winch to wind up the axis at pleasure. The saw employed is at the edge
of a hollow cylinder (on the same plan as that described by as for trepanning, under the article ANNULAR SAW), and this hollow cylinder is turned by the spindle through the medium of cross-arms, through which the axis slides ; and, in order to give the requisite force to the annular saw, the top of the tube to which it is fixed is loaded, .provided its own weight be insufficient : the motion given to the saw, though circular, is reciprocating. To effect this, a rope passes round the pulley at the upper part of the axis, and the two ends of the rope are conducted in opposite directions over two vertical pulleys, over which the two ends of the rope respectively fall, where they are each furnished with a cross handle ; one workman takes bold of one handle, and another workman the other, and pulling alternately the pulley at the top of the axis, together with the annular saw, qi made to reciprocate circularly, cutting an annular groove in the block of stone. A barrel of sand and water is made to deliver these essen tial auxiliaries to the saw in the following manner :—it is directed to the upper end of the axis above the tube; which it enters, and runs down into the annular groove under the edge of the saw, whence it flows upward by the pressure of the continued descending current on the opposite side, and thus carries off the sludge clear of the saw. Stone tubes of this kind were employed by the Man chester Water Works Company.
Elastic tubes of Indian rubber are extensively used for the transmission of gas and corrosive liquids; and they are admirably manufactured by Mr. Thomas Hancock, of Goawell-street Road. Mr. Thomas Skidmore, an American gen tleman, whose process is a good one, is as follows :—Take a cylindrical rod of iron of the desired length, round this closely coil annealed wire in the manner of a spiral spring, care being taken that the edges of the coiled wire shall touch each other, but shall, at the same time, not be so firmly wound as to prevent its slipping off the rod : then cover the wire with tape spirally from end to end, and upon it lay strips of Indian rubber, wound in a similar manner, with their fresh cut and clean edges lapping upon each other. Then bind these down tightly with another coil of tape : after this withdraw the rod, and boil the tube in water for an hour or two ; when cool, remove the wire and tapes, and an Indian rubber tube will be produced, which, though rough, will be perfectly sound if the process has been properly conducted.