SPINNING. There are two entirely distinct manufacturing opera tions to which this name is given—the one relating to animal and vegetable fibres, and the other to certain soft metals.
Fibre Spinning.—This kind of spinning consists in forming a flexible cylinder of greater or less diameter, and of indeterminate length, out of vegetable or animal fibres, arranged as equally as possible alongside and at the ends of each other, so that, when twisted together, they may form an uniform continuous thread. The primitive modes of spinning by the spindle and distaff, and by the spinning-wheel, which are still extensively practised in the East, and not entirely superseded in some remote districts of Scotland, only enable the spinner to produce a single thread ; but with the almost automatic spinning-machinery which has been called into existence by the cotton manufacture, one individual may produce nearly two thousand threads at the same time. The history of the series of inventions by which this result has been gradually attained has been already given under COTTON AIANUFAC TunE ; together with wood-cuts and descriptions of some of the chief machines. The spinning of flax, silk, and wool partake of the same general character as that of cotton ; so far as they differ they will be found noticed under LINEN MANUFACTURE; SILK MANUFACTURE; and WOOLLEN AND WORSTED MANUFACTURE.
Metal Spinning.—This is a peculiar branch of Birmingham and
Sheffield manufacture, in which articles of use and ornament are pro duced without forging, casting, stamping, or cutting, by bringing into play the ductility of the metal. The metal employed is chiefly one or other of the soft mixed white metals, such as Britannia metal. Tea pots, and such-like articles, are shaped in this metal almost entirely by the process of spinning. There is first prepared a wooden mould, of the exact size and shape ; and this mould is fixed upon a lathe. Then a circular piece of the thin sheet metal is taken and fixed temporarily in contact with the bottom or flat surface of the lathe. Burnishers and smooth tools are then pressed cautiously against the metal, while the mould is rotating, and made to conform to all its curvatures— stretching out a little to cover the convexities, and compressing a little to cover the concavities. The ductility of the metal alone enables it to do this ; the bending takes place gradually, so as to enable the particles of the metal to accommodate themselves to their altered position. Teapots, plated candlesticks, dish-covers, bell mouths of musical instruments, &c., are made by a succession of processes of which this is the chief ; and a large quantity of cheap Birmingham jewellery is worked into form in a similar way.