Fig. 40. Fig. 41. Fig. 42. Fig. 43.
We have never made any metal pipes ourselves, and we doubt if our readers will do well to embark upon an undertaking requiring special "plant" and appliances in a separate workshop, and calling for great dexterity and neatness in a class of operations familiar only to trained artisans. For the information, however, of those who choose to make the experiment, we may explain that the metal sheets from which the pipes are made are thus produced:— "The ingredients (viz. tin and lead in various proportions) are melted together in a copper and then cast into sheets, a process effected by pouring it in a molten state into a wooden trough, and running the trough rapidly along a bench faced with tick. The metal escapes from the trough through a narrow horizontal opening at the back, leaving a layer of metal behind it as it proceeds; and the wider the cutting is, of course the thicker will be the sheet of metal produced. After being cast to an approximate thickness, the metal is planed down to the precise thickness required. It is then cut into portions of the shape necessary to give to the pipes the required size and form, and is thus finally worked up."[2]
[2] Hopkins and Rimbault, p. 76.
The three parts which compose the pipe are first separately prepared. The sheet of metal is rolled round a wooden cylinder or cone, called a mandrel, and the edges are soldered together. The extreme neatness of this soldered joint is secured by smearing the metal with composition, which is scraped off at that part only which is to retain the solder; but a steady hand, and long familiarity with the manipulation of the heated copper tool and with the properties of soft solder, are absolutely essential to success.
At the lower part of the body thus soldered, the mouth is formed by flattening a portion of the cylinder and by cutting away a horizontal slip of the metal. The width of the mouth is to be in all cases a quarter of the circumference of the pipe. In the case of large pipes the mouth is formed by cutting away a piece of metal of considerable size, and replacing it by a sheet called the "leaf," having the mouth cut on its lower edge.
The foot is formed in a similar manner, and has a flattened portion corresponding to that of the body.
The language, or languid, is a circular disc of much thicker stuff, bevelled off round its periphery, which is altered into a straight line at that portion which will lie beneath the mouth when the pipe is complete.