A trough called the pan ran along the whole length of the table, and into this the melted lead was poured from the melting pot. There were two ways of making the sheet lead: one of them was to tilt the trough up, and pour out the lead on to the table, two men immediately passing a wooden strike over it so as to spread it evenly over the whole surface. In this case the thickness of the sheet of lead depended on the distance between the edge of the “strike” and the surface of the sand. Another way was to have a narrow opening all along the bottom of the trough, the trough itself moving from end to end of the table as the lead flowed out. When this method was used the thickness of the sheet depended on the size of the opening, and the rapidity with which the trough was moved along the table. Neither of these methods are now used, the lead being rolled into sheets by machinery. Water-pipes are made by lead being cast in moulds with a steel rod passing through their middles, according to the size required. The lead is poured into the space between the rod and the mould. After it is cool the rod is drawn out by machinery, and the mould which is made in halves is opened and the pipe taken out. The pipe is then much thicker and shorter than is required for use, but it is afterwards drawn between powerful iron rollers with grooves cut in their surfaces, an iron rod being again placed inside it. As these grooves gradually decrease in size, and the pipe is drawn through several, it is very considerably lengthened, and at the same time diminished, in thickness, by the time the operation is finished. Another method of making lead pipes is by the use of the _forcing pump_, which pumps the melted metal out of the boiler into a mould containing a “mandril,” or pipe of the required size. Pipes made in this way do not require to be rolled. [Illustration: Forcing Pump.] The work which the Plumber is called upon to do on the roofs of houses requires experience before it can be properly performed. The foundation of the roof which is to be covered with lead is made either of boards or plaster, so that the surface may be even, and if it be of boards they must be thick and well seasoned to prevent their warping. The foundation slopes a little in order to carry off the rain towards one end. When the roof is so large that it needs two widths of lead, there are three ways of joining the edges of the lead together: one is by fastening to the roof long slips of wood (flat at bottom and round at top) at the places where the lead will be joined. Over these strips the edge of the first sheet of lead is folded and hammered down quite close, then the edge of the second sheet is folded and hammered over that, so that water cannot get between them. This is called “rolling.”