TURNER'S YKLLOW. 



TURNING. 



440 



perehlorid* of tin, and print* the mixture, which is in a great measure 

 oluble, u|n Turkey red cloth, raiting the blue colour afterwards by 

 rrri"c the cloth through a dilution of chloride of lime, containing an 

 +T~~ of lime. The chief object of this operation is to discharge the 

 red aud produce white patterns, where tartaric acid is printed upon 

 the cloth, but it has also the effect incidentally of precipitating the 

 blue pigment and peroxide of tin together on the cloth, by neutralising 

 tin- chlorine of the perchloride of tin. This blue is believed to resist 

 the action of alkalies longer than ordinary Prussian blue. 



T f 1! N K K'S Y K I . I ,t i \V. ttuw I Y<Uo : Patent YtUme. This is an 

 oxvchloride of lead, which may be prepared by different processes. 

 When litharge, or the protoxide of lead, is acted upon by a solution of 

 common salt, there are formed soda, which remains dissolved, and a 

 white compound, which is hydrated oxychloride of lead ; and this, 

 when heated, loses water, becomes of a yellow colour, and is the com- 

 pound required. It is composed nearly of one part of chloride and 

 nine parts of oxide of lead : it may also be obtained by heating chloride 

 and oxide of lead together in the requisite proportions, or by heating a 

 mixture of one port of chloride of ammonium with ten park of pro- 

 toxide of lead. In fusing these compounds, it is requisite to be 

 extremely careful to avoid any admixture of carbonaceous or combus- 

 tible matter, as that would reduce a portion of the oxide of lead to its 

 metallic state, which would injure the colour of the product. [LEAD : 

 OxyrUoridtt of Lead.] 



tl'ltXlXlt ia the art of giving circular forms to articles of wood, 

 ivory, metal, and other materials. The kinds of wood mostly used fur 

 common toys are alder, beech, birch, and willow ; for the best Ton- 

 bridge ware, holly, chesnut, sycamore, apple, pear, and plum ; for hard 

 general turnery beech, box, elm, oak, and walnut ; and mahogany and 

 pine for various purposes. 



Nearly all kinds of turning are effected by the aid of the lathe. The 

 principles of this valuable machine may be summed up in a few words. 

 For every point marked by the workman, it produces a circle ; and it 

 may be described as a machine for moving the material to be wrought 

 in such a manner that, being fixed opposite to the tool, any point in 

 the circumference will act upon the whole circle in precisely the same 



Pale-lathe. This is the primitive and most simple kind of lathe. It 

 consists of two upright pieces, each having a conical iron or steel point 

 fixed on the side opposite the other, the two points being exactly in a 

 line ; one of these uprights, or puppet-heads, as they are called, is 

 stationary ; the other can be moved along and fixed at any part of 

 the bed by a wedge beneath. The wood t& be turned being cut of 

 proper length, the centre of one of its ends is pressed against the 

 point of the fixed puppet; the point of the other puppet is then 

 brought against the centre of the other end, and the puppet wedged 

 firmly in its place. Over the lathe, and at right angles to it, is a long 

 flexible wooden pole or lath, whence the name lathe ; one end, fixed 

 firmly overhead ; the other, just over the end of the work nearest to 

 the left-hand puppet, has a cord or catgut attached to it, which passes 

 once or twice round the work, and is fastened at the lower end to a 

 treadle. The depression of the treadle and counteraction of the pole 

 give an alternate rotatory motion to the work. The cutting tool is 

 held upon the top of a fixed piece, between the two puppets and close 

 to the work, called a ml, but can only be applied during the fall of the 

 treadle ; and thus a great loss of time is occasioned. On this account 

 the pole lathe is now but little used. When commencing, a groove is 

 cut to the extreme left of the work for the cord to work in ; and if 

 it is required to use that part, the band is afterwards shifted to a 

 finished part. The beginner has one great difficulty to overcome in 

 turning soft wood. The tool requires to be held firmly almost on the 

 top of the work, and the superfluous material shaved off; while the 

 softness of the wood and the velocity with which it revolves cause the 

 work to be easily spoilt by the least unsteadiness of hand. In other 

 turning, the tool is held nearly opposite to the centre of the work, and 

 the superfluous material is scraped away with little comparative danger 

 of accident 



A modification of the primitive pole-lathe is used by watch-case 

 makers, on account of the facility with which it can be arrested at 

 any |int of it* rotation. Some case-makers, the French in particular, 

 make use of a large turning-tool instead of a lathe. It consists of an 

 iron tr upon which slide three puppets, two to support the mandril 

 with its back (crew, and the other the rest ; a long steel bow worked 

 by the left hand serves instead of the pole and treadle. This tuniing- 

 tool works easily, cost* but little, and where many workmen are 

 employed effect* a great saving of room. Tools of this sort, from six 

 inche* to two feet long and upwards, are in use among jewellers, 

 goldsmiths, watch and clnckmakera, and many other artificers; and 

 others without any mandril, in which the work is held between two 

 j>iiiU, as in the pole-lathe. One of this latter sort may be converted 

 into a very useful lathe for small work at a trifling expense, and still 

 answer as a turning-tool if required. 



The I'uUtr$.wktd i* the simplest description of rotatory lathe ; but 

 it differs from other lathes in being vertical instead of horizontal, c, 

 fg. 1 , is an iron crank, upon the lower part of which is placed a heavy 

 fnot-wli-,-l, f ; the lower end of the crank works upon a centre, r, fixed 

 lloor; the upper in a collar, B, fastened to the work-bench, A. 

 and support* the turnboard or chuck, D, upon which the clay to be 



worked is placed. Motion is given to the crank by means of a treadle 

 placed at the back, and connected with the throw of the crank by a 



1 



g. i. 



hook or rod. For large work the wheel is provided with a winch and 

 bevil gear, and is turned by a boy. [EARTHENWARE.] 

 Foot-lathe. Fig. 2 is the front-view of a foot lathe, adapted to all 



Fig. 1. 



'K 



F T 



I 



ordinary work, whether in metals, ivory or wood. The Deadstock, I! H, 

 is of cast-iron, with a conical steel ring let into the front puppet within 

 which the mandril works. A steel-pointed screw in the back of the 

 headstock keeps the mandril steadily in its place. The beds are of cast- 

 iron, shown in the end view, Jig 3, which also shows the manner in 

 which the headstock is fitted upon aud between the beds, to which 



Fig . 



it is firmly fastened by two screws, A A, fy. 2. The crank, c, is of 

 wrought-iron, supported at each end by a screw, B, fy. 2, 8, in thu 

 standard of the lithe. The fly or foot wheel, K, has four or five groove* 

 on iU edge, and gives motion to the mandril by means of a catgut band, 

 which connects it with the smaller part of the mandril pulley, r. The 

 object of having several grooves upon the wheel and pulley is to allow 

 of the speed of the lathe being regulated according to the sort of work 

 to be turned. But this arrangement only modifies what is called the 

 quick motion. It is frequently necessary that the mandril should 

 move more slowly than the crank ; for which purpose a large pulley is 

 placed upon the mandril, and a small one upon the crank, and the two 

 are connected by a band. The treadle is formed of a long iron liar 

 suspended between two points at the bock of the frame, D, fy. 2 and 3, 

 and carries two shorter transverse bars at right angles, passing under 

 the throws of the crank, and being connected with them by the hooks, 

 T, E : the front ends of these two pieces are screwed to the treading- 

 boord, w. The standards of the lathe ore prevented from altering 

 their position by a rod passing close to the ground, and screwed to 

 each standard at Q. The front-head, o, is of cast-iron fitted on to the 

 beds nearly in the same manner as the headstock. The point of the 



