810

T U R

TUR

Mr. Maudslay uses in his manufactory, instead of being workedby the foot, as represented in fig. 2, are worked by the hand; thewheel and fly-wheel which the men turn work by a strap on ano-ther wheel, hxecl to the ceiling directly over it; on the axis ofthis wheel is a larger one, which turns another small wheel or pul-ley, fixed to the ceiling, directly over tbe mandrel of the lathe ;and this last has on its axis a larger one which works the mandrelD, by a band of catgut. The following is a description of Mr.Smart’s newly invented lathe for turning cylinders of wood for thepurpose of tent-poles, pickets, handles for tools, &c. &c. the ope-rations of which are so readily performed, that from octagonal barsof yellow deal, five feet and a half long, (previously prepared bymeans of a circular saw) one man, besides two labourers, to turnthe wheel, will turn out 600 perfectly cylindrical poles, in thespace of twelve hours. A A, (fig. 9,) represents the standards forsupporting the great wheel, that gives motion to the lathe ; theseare supported by pieces of board 1315 spiked to the ceiling or joistsabove, and by others CC affixed to the floor of the workshop.The great wheel DD is grooved round the edge for receiving theendless screw B and E, E, and is put in motion by the winchhandle FF. G and A are the standards of the lathe, firmly fixedto the floor, and carrying the side-pieces or bed II; the standardG is tall enough to act as a fixed puppet, and has a screw a work-ing through it, for supporting the end of the mandrel or spindle ofthis lathe, as in the common lathe. K, L, and M, are three otherpuppets that can be fixed in any place desired, by wedges beneaththe bed as usual. To the puppet K is screwed a thick iron plateb, which has a conical socket, nicely turned and polished, for re-ceiving the mandrel: this puppet is further steadied by a brace N,screwed to it, and to the floor of the shop. To the puppet K amiL two bars oo are fixed by screws, and the same are further sup-ported and steadied by three short puppets PPP. The mandrel,and its pulley Q, are nearly of the common construction, exceptthat the end c has a steel-point in its centre, and two shorter pointsfor preventing the octagonal piece of wood intended to be turnedfrom slipping or turning without the mandrel. The puppet L hasa square-pointed bar d fitted to it; and the puppet M has a screw,worked by its handle e, which by means of a collar advances ofdraws back the bar d. R is a piece of wood, fixed to the bed andto the floor, for the purpose of carrying a pulley/, whose use is toprevent the wheel-band EE from wearing by friction at the placewhere it crosses. Fig. 10 and 11, represent the gouge and plane,successively used instead of the common turner’s chisel, &c. thepieces of board aa are screwed to the block b, just at the properdistance of the outsides of the bars oo, (fig. 9,) so that when thetools, (fig. 10 and 11,) are placed on them, they can be slid alongsteadily, between the puppets K and L ; the holes cc being soadapted as to suit the mandrel and bar c and d as centres, andtheir diameters are sufficient to let the octagonal bar intended tobe turned pass through them, without touching ; d, (fig. 10,) is apiece of tempered steel, formed as a gouge, and screwed fast tothe side of the block, in the proper position for roughing off theangles of the octagonal bar, as it advances, and turns through thehole c. c, (fig. 10,) is a flat piece of steel, like a plane-iron (shewnseparately at/), which is so fixed by a screw, that it may smoothor complete the cylindrical surface of a pole, already gouged asabove, which is advanced, and turned through it. The operationis thus performed : The two tools, (fig. 10 and 11,) are placed onthe bar oo, (fig. 9,) and shoved close up to the puppet I; thesquare bar being long enough for its point d, then to projectthrough the centres of the holes cc, (fig. 10 and 11.) The workmanthen takes an octagonal pole, enters the centre-pin of the mandrele into the centre of its end, and the point d into the centre of theother end, turning the handle e sufficiently to allow the pole to besteadily turned : the wheel D is then set in motion ; the workmanpushes the gouge-tool, (fig. 11,) forwards, towards the puppet K,which, as it advances quickly, strikes off the angles of the pole ina rough or screw-like form. When the gouge-fool, (fig. 8,) hasadvanced to the end of the pole, the finishing-tool, (fig. 10.) is inlike manner shoved forwards by the workman : and as it advances,the pole is turned into a complete and smooth cylinder. Theprojection of the mandrel be, (fig. 9,) is sufficient' to admit thegouge and plane tools, to advance so as to clear the end of thepole ; and by turning back the handle e, the same can be takenout of the lathe as soon as it is stopped. The velocity of the

mandrel Q is such, as to make upwards of 1200 turns per minute.For turning ovals, a lathe of somewhat a different construction isused, or an oval may be formed by placing the wood, or whateveris to receive that shape, obliquely on the lathe. There are severalother ingenious methods of turning : but our limits do not per-mit us to enter upon them. Indeed the act of turning is so exten-sively applicable, that it would require a volume to describe itsuses, and the methods of practising it. Every round thing whichis made by human hands may be referred to this art, as one of itsproducts. The largest columns, the most ponderous artillery, andthe minutest pivots of watch-work, with all wheel-work, rotatorymachines, vessels, &c. are worked in this method. For the stain-ing of wood, &c. to prepare it for turning, see Wood, Bone, &c.

TURNIP. See Brassica, and Husbandry.

TURNSOL, a dye-stuff manufactured in Holland, from thatkind of lichen called Orchil, or Lichen Rocella, see that arti-cle; or, when that cannot be procured, the large oak-moss, afterbeing dried and cleaned, is reduced to powder, and employed forthe same purpose.

TURPENTINE, a transparent resinous substance , whichexudes naturally, but is chiefly obtained by incision, from variousspecies of the pine-tree ; and is divided into four kinds, namely1. The Chian, or Cyprus turpentine, is derived from the Pistachiatree : it is of a thick consistence, resembling that of honey; has afragrant smell ; and a bitterish pungent taste. 2. The Venice tur-pentine, which exudes from the Larch-tree, has a strong smell,and a hot disagreeable taste: it is less viscid than any of the otherturpentines, and generally of a clear whitish or yellowish cast.This and the preceding species pay, on importation, a duty of A\d.per lb. 3. The Strasburgh turpentine possesses an agreeable aro-matic odour, but an uncommonly bitter taste; is neither so thickas the first species, nor so thin as the second ; but clearer, and lesstenacious than either; being commonly of a yellowish brown co-lour : it is imported from Germany , and charged with a duty of14s. %d. per cwt. 4. The common turpentine is extracted fromthe spruce-fir: it is of a dark-brown colour; of the consistence ofhoney ; and has the most disagreeable odour and taste of all thedifferent species. All the turpentines yield, on distillation, an es-sential oil, which is extremely pungent. On account of their diu-retic and tonic properties, they are often successfully prescribed incalculous complaints. The Venice turpentine is preferably re-commended as a diuretic, and detergent; while those of Chios and Strasburgh are used as corroborants. The common sort ismostly employed as an ingredient in the plasters used by farriers ;and its essential oil, obtained by distillation, is consumed partly inthe preparation of gin, and partly by house-painters; as likewisefor the different varnishes in the floor-cloth, umbrella, and many rother manufactures. Lastly, when combined with honey, this oilis supposed to afford a powerful remedy in rheumatic affections.

TURQUOISE, a substance of a pale sky-blue colour, passinginto indigo-blue, and pale apple-green. It occurs in mass, or dis-seminated. Its fracture is even. Its hardness is nearly equal tothat of glass ; it is difficultly frangible. Specific gravity 3. IS. It

is composed, according to Bullion la Grange, of

Phosphate of lime.80

Carbonate of lime. 8

Phosphate of iron, with a trace of manganese. 2

Phosphate of magnesia. 2

Alumina. 1

Water. 6

Loss. 1

100

Turquoise is generally considered as fossil-bone, or ivory pene-trated by oxide of copper ; it appears, however, from the aboveanalysis, that the colouring matter is phosphate of iron. Theoriental turquoises are found near Meched in Persia , also inmount Caucasus, in Egypt and Arabia . The occidental ones 3 refound in Languedoc in France, and in Hungary .

TUR R./EA, in hotanv, a genus of plants in the class decandria,and order monogynia; natural order, Compnsitic. Calyx five-toothed ; petals five; nectary toothed, cylindrical, bearing theanthers at the mouth between the teeth ; capsule pentacoccous;seeds two. There are five species.

TURRITIS,