CASTING.--From a drawing the pattern is made in wood--⅛ of an inch to the foot longer in case of cast-iron, and ³⁄₁₆ do. in case of brass to allow for shrinking. The pattern is laid in sand, often contained in a casting frame, which, from its plasticity, non-fusibility, and other properties lends itself admirably for mould making. The mould is dusted over with charcoal, or with a mixture known as founders’ dust, and the casting then made by pouring metal in. With small articles in brass, metal patterns are used. For gold articles, such as wedding rings, an iron frame is used, filled with the finest red sand. For small gold work, the cuttle fish bone is used as a mould, the pattern being pressed in the same manner as in sand.[46] A special feature in the process of casting in our district is the production of “chilled” castings for rolls. The mould for the barrel part of the roll is a heavy cylindrical casting of iron truly bored out to a size sufficient to allow of the roll being turned to the required size. The molten iron is run into the mould sidelong, and from the bottom, so as to give the metal a rotatory motion. This rotatory motion causes the dust and slag to keep in the centre, leaving a pure metal in contact with the mould. This metal chilled by contact with the massive metal mould, produces the hard and close texture required.[47] Keys, stirrups, hob nails, and many small articles are produced by casting, the casting being afterwards rendered malleable by the process of cementation, which consists in packing the articles in an iron box with powdered hæmatite, and heating from three to seven days. Iron castings are also annealed by packing with cinders in a box, which is then heated for some time, as with the malleable cast iron. ROLLING, WIRE AND TUBE DRAWING.--Iron, brass, steel, and German silver are used up in the form of sheet, wire, and tube. With large firms producing finished articles, these processes are done on the premises, but there are several works devoted to the production of sheet metal, wire, or tube only, and rolling for the trade. In the jewellers’ district, the cast ingots of the precious metals are taken to rolling mills in the neighbourhood to be rolled down to the required degree of fineness. For some articles, such as spoons, where a blank is required of varying thickness, strips of metal are thinned in parts by what is known as “cross rolling,” the rolls being exposed at one end, so that a strip of metal may be passed through, which is thus thinned down at one end.