Lead pipe is either formed by bending thin sheet lead round a cylindrical mould, and soldering the joint; or when the pipe is less than four or five inches in diameter, it is formed by casting a thick cylinder of lead with a small bore, and about five or six feet long. A long smooth iron rod, a little larger than the bore of the cylinder, is forced into this, and then the cylinder is gradually drawn through a succession of circular holes, decreasing in diameter, in a steel plate, by means of a powerful draw-mill, worked by a steam-engine. The lead is by this process extended out over the iron rod, which preserves the bore of the pipe of an equal diameter, and when the pipe is sufficiently reduced in thickness, the rod, or _triblet_, is forcibly drawn out, and the pipe left with a smooth bore, ready for use. Attempts have been made to form lead pipes wholly by casting; an outer mould and an inner core being so adjusted as to leave a space between them, into which lead might be forced while in a melted state; but this method has not been practically worked out to any great extent. The Process of Plumbing. When a roof is to be covered, or a cistern lined, with lead, the sheet of the metal is unrolled on a level floor, and made free from creases and undulations, by beating them down with a heavy wooden _flogger_, formed like a roller with a flattened side, and a handle to it. The plumber then draws on the lead the form into which it must be cut to fit the surface it is intended to cover, and afterwards cuts through the lines described with a strong sharp knife. The piece is then rolled up again for facility of carriage, and raised by tackle into its intended situation, it being placed there so that when again unrolled, it may lie in the proper situation and position on the boarding. The sheet is then again beat out flat as before. The next sheet being put into its place, and so that the edges of the two may overlap about one and a half or two inches, the workman proceeds to make the joint, or to solder the two sheets together. The first step for this purpose is to scrape the two edges or borders of the sheets that are to come in contact quite clean and bright, with a tool constructed for this purpose, consisting of a small triangular bit of steel ground sharp at its edges, and fastened at right angles on an iron socket, fixed in a handle. When these borders of the lead are quite clean, they are painted over with black-lead paint, to prevent their tarnishing, or _oxidising_ again, as the solder will only adhere to a clean pure metallic surface. The paint also serves as a flux to cause the solder and lead to melt together, and thus make a close joint.