inch, then they will all move equally, and determine with precision the eccentricity and diameter of the circles, and also the depth to which you wish to cut them by your tool.

One example will now be sufficient to explain the application; and, for the sake of being as perspicuous as possible, we will suppose the several regulating screws to be such that one turn shall move the plates and tool forward onetenth of an inch. Now, suppose it is required to describe a circle whose eccentricity shall be half an inch, and radius one inch, and also that the depth to which we wish to cut it be the hundredth part of an inch, we must proceed as follows: turn the screw I of the chuck forwards five turns, which will be for half an inch for the eccentricity, the screw of the rest G ten turns, which will make the radius one inch; then set your lathe in motion, and turn the screw II of the rest gradually one-tenth of a turn, and you will have described the circle required.

It now only remains to describe how we are to produce a series of eccentric circles about a common centre: this is easily performed by means of the toothed wheel E, which is commonly di. vided into ninety-six parts or teeth. Or we may employ three times ninety-six, or 288 teeth; and hence we can describe, round the common centre, the like number of circles, or any number from unity to 288. Thus, if it be required to draw 288 eccentric circles round the centre F, we must for every circle move the wheel E forward one tooth, till the whole be completed. Again, if we wish forty-eight eccentric circles round the common centre, we must divide 288, the whole number of the teeth, by forty-eight, which gives six, that is to produce forty-eight eccentric circles, we must, for every circle, move the wheel forward six teeth, and thus we may draw any number of circles equidistant from each other, round the centre F; with this limitation, that it must be such a number as will divide 288 without a remainder; for if there be a remainder the circles will not close or meet exactly, but will leave a space unoccupied.

We shail conclude this article with a number of receipts which every turner ought to be acquainted with.

1. The method of moulding boxes both of shell and horn. In the first place form a proper mould, which must consist of two pieces; viz. of a circle about half an inch thick, which should slope a little in order to draw out the moulded shell the more easily; and a ring fitted to the outside of the circle, so that both together make the shape of a box. These two pieces being adjusted it is necessary to round the shell to be moulded of such a size that, when moulded, it will be a little higher than the ring of the mould that there may be no deficiency. The mould is then to be put into a press on a plate of iron exactly under the screw of the press; put then the shell upon the circle of the mould, so that its centre also is exactly opposite to the screw of the press; then take a piece of wood formed into a truncated cone, and not so thick as the diameter of the circle of the mould, nor so deep as the ring; then put a plate of iron above the cone, and screw down the press gently and cautiously till the

whole is well fixed; then plunge the whole into a cauldron of boiling water placed above a fire. In eight or ten minutes the shell or horn will begin to soften; screw the press a little firmer that the wooden cone may sink into the softened shell: repeat this from time to time till the cone is quite sunk in the mould; then take out the press and plunge it into cold water. When it is cold take the box now formed out of the mould and put into the inside of it a new mould of tin exactly of the form you wish the inside of the box to be; do the same with the outside, put it again into the press and plunge it into boiling water; screw the press gradually till the box be fashioned as you desire.

2. Method of preparing green wood so that it will not split in the turning.-Having cut your wood into pieces of a proper size, put it into a vessel full of a ley made with wood ashes. Boil it there about an hour; then, taking the cauldron off the fire, allow the ley to cool; then take out the wood and dry it in the shade.

3. Method of giving an ebony-black to hard and fine woods. After forming the wood into the destined figure rub it with aquafortis a little diluted. Small threads of wood will rise in the drying, which you will rub off with pumice-stone. Repeat this process again, and then rub the wood with the following composition:-Put into a glazed earthen vessel a pint of strong vinegar, two ounces of fine iron filings, and half a pound of pounded galls, and allow them to infuse for three or four hours on hot cinders. At the end of this time augment the fire, and pour into the vessel four ounces of copperas (sulphate of iron) and a chopin of water, having half an ounce of borax and as much indigo dissolved in it; and make the whole boil till the froth rises. Rub several layers of this upon your wood, and, when it is dry, polish it with leather on which you have put a little tripoli.

4. Method of giving to plum tree the color of brazil wood.-Slake some lime with urine, and bedaub the wood over with it while it is hot: allow it to dry; then take off the coat of lime and rub it with chamois skin well oiled. Or steep your wood in water, having a quantity of alum dissolved in it: then, having allowed Brazil wood to dissolve in water five or six hours, steep your wood in it, kept lukewarm during a night; and when it is dry, rub it, as before directed, with chamois skin well oiled.

5. Method of giving a fine black color to wood.

Steep your wood for two or three days in lukewarm water in which a little alum has been dissolved; then put a handful of logwood, cut small, into a pint of water, and boil it down to less than half a pint. If you then add a little indigo, the color will be more beautiful. Spread a layer of this liquor quite hot on your wood with a pencil, which will give it a violet color. When it is dry, spread on another layer; dry it again and give it a third: then boil verdigris at discretion in its own vinegar, and spread a layer of it on your wood: when it is dry, rub it with a brush, and then with oiled chamois skin. This gives a fine black, and imitates perfectly the color of ebony.

6. Method of cleaning and whitening bones be

TURQUOIS, MINERAL, or calaite. Colors smalt blue and apple green. Massive, disseminated, and imitative. Dull. Fracture conchoidal ur uneven. Opaque. Harder than felspar, but softer than quartz. Streak white. Specific gravity 2.86 to 30. Its constituents are alumina 73, oxide of copper 4.5, water 18, oxide of iron 4.-John. It occurs in veins in clay-iron-stone, and in small pieces in alluvial clay. It has been found only in the neighbourhood of Nichabour in the Khorassan, in Persia. It is very highly prised as an ornamental stone in Persia and the neighbouring countries. Malchite yields a green streak, but that of calaite is white. Bone turquois is phosphate of lime colored with oxide of copper.

TURQUOISE, n.. s. See TURKOIS.

One shewed me a ring, he had of your daughter for a monkey.

-Out upon her! it was my turquoise; I had it when I was a bachelor. Shakspeare. Merchant of Venice. TURREA, in botany, a genus of plants in the class of decandria and order of monogynia; ranking, in the natural method, under the fortyninth order compositæ.

TURRET, n. s. I Latin turris. A small TUR RETED, adj. eminence raised above the rest of the building; a little tower turreted, with a turret or turrets.

Discourse, I pr'ythee, on this turret's top.

Shakspeare.

TURRETIN (Francis), minister and professor of divinity at Geneva, his native place, was born in 1623. Having studied at Geneva, Leyden, Saumar, Montauban, and Nismes, with great success, he was admitted into the ministry in 1648, and served at the same time the French and Italian churches at Geneva. Two years after he was offered the professorship of philosophy, which he refused; but accepted the invitation of the church at Lyons. He was recalled to Geneva a year after, being wanted to give lec*ures in divinity; which he began in 1653. He was sent to Holland in 1661, to procure money

for the city of Geneva. He had in that journey all the success he could wish; and gained such a character that he was strongly importuned by the Walloon churches at the Hague and at Leyden to enter into their service. On his return he resumed the functions of his place, and continued there till his death. He died in 1687, with the character of a man of great merit; eloquent, judicious, laborious, learned, and zealous for orthodoxy. His works were published by his son, in 3 and in 4 vols. 4to.

TURRETIN (John Alphonsus), son of the above, was born at Geneva, in 1671; and became the

first professor of ecclesiastical history, in that republic. He wrote an Abridgment of Ecclesiastical History; Sermons, and other works. He died at Geneva, 1737.

TURRITIS, tower mustard, or wall cress, in botany, a genus of plants belonging to the class of tetradynamia, and to the order of siliquosa; and in the natural system ranging under the thirty-ninth order, siliquosæ. The siliqua is very long and angulated; the calyx connivent and erect; the corolla is also erect. There are three species; two of which are natives of Great Britain; viz. 1. T. glabra, and 2. T. hirsuta.

TURSHEEZ, a considerable city of Korassan, Persia, on the borders of the Great Salt Desert. The old city (Sultanabad) is small; but to this a new one has been added, in which the governor resides. Both together contain about 20,000 inThe trade arises chiefly from the importation of habitants, among which are 100 Hindoo families. indigo and other drugs from the westward; wool, cloth, and rice from Herat. The chief export is iron. Between this and Herat the country is in general wild, mountainous, and uncultivated, 160 miles W. N. W. of Herat.

TURTLE, n. s. Į Saxon ruptle; Fr. tor TURTLEDOVE. Storelle; Italian tortorella, A species of dove: also a kind of tortoise. Take me an heifer and a turtledove. Gen. xv. 9. When shepherds pipe on oaten straws, And merry larks are ploughmen's clocks; When turtles tread.

Shakspeare. Love's Labour Lost. We'll teach him to know turtles from jays. Shakspeare. Galen proposed the blood of turtles dropt warm from their wings.

Wiseman.

TURTLE, in icthyology. See TESTUDO. TURTLE, AMERICAN, a machine invented by Mr. David Bushnell, of Saybrook, in Connecticut, for sub-marine navigation. The Catamarans, so pompously submitted, and so expensively at tended to, by the late Mr. Pitt, as being the ori ginal invention of Mr. Fulton, were direc imitations, or rather copies, of the American turtle. It is a decked boat, to go under water, and several persons have gone under water many leagues. The difficulty is to provide the persons in the boat with fresh air for respiration, and this is contrived by having a reservoir of air, of suitable dimensions to the size of the boat, and the number of persons in it. By means of a condensing pump, the air in this reservoir is condensed about 400 times; and by a spring the air is let out at intervals, as circumstances require; the impure air being rectified by carbonic

of the working classes. The revenue is about £600,000. The church establishment consists of three archbishops and sixteen bishops, whose incomes, and still more those of the inferior clergy, are very limited. The military force, exclusive of the volunteers or militia, does not amount to 3000 men; its navy is very insignificant.

In religion the Tuscans, with a slight exception (Jews to the number of 16,000), are Catholics, but exempt from several of the defects and bad habits of their Italian countrymen. They speak their language with considerable purity, and possess scientific institutions, which rank high among provincial academies.

To readers of ancient history Tuscany will be known under the names of Etruria and Tyrrhenia. Its territory, early peopled, contained twelve towns of note, in the ages which followed the foundation of Rome. About the year of Rome 474, after the conquest of the Volsci, qui, and other small tribes, but before the more hazardous contests with Pyrrhus and the Carthaginians, the Romans completed the subjugation of Etruria. It remained in their possession between 700 and 800 years, until overrun by the barbarians. Held at first as a duchy and fief of Lombardy, it was afterwards restored to independence; but, towards the beginning of the thirteenth century, the continued divisions which agitated it led first to a change in the form of government, and eventually to the ascendency of the Medici family, which long ruled with the title of grand duke, but became extinct in 1737. Their place was filled by the duke of Lorraine. That prince, the husband of Maria Theresa, becoming afterwards emperor of Germany, vested the grand duchy in his second son. From him it descended to the grand duke Ferdinand, brother of Francis II. of Austria. In the wars of the French revolution the policy of Tuscany was to avoid any active participation in the contest. did not, however, long exempt the country from change. By the treaty of Luneville (February 1801) the grand duchy of Tuscany received the title of kingdom of Etruria, and was transferred to the hereditary prince of Parma: in the subsequent incorporations of Buonaparte it was declared an integral part of the French empire, as we have seen.

This

TUSCULANUM, a villa belonging to Cicero, near Tusculum, where he wrote his Questiones Tusculanæ. Formerly the villa of Sylla; now called Grotta Ferrata. TUSH, interj. Gothic thus; Dan. tys. An expression of contempt. Tush, say they, how should God perceive it? is there knowledge in the Most High? Psalm, lxxiii.

Sir Thomas More found fault with his lady's continual chiding; saying, the consideration of the time, for it was Lent, should restrain her. Tush, tush, my lord, said she, look, here is one step to heaven-ward, shewing him a friar's girdle. I fear me, quoth Sir Thomas, this one step will not bring you up a step higher.

Camden's Remains.

Tush, never tell me I take it much unkindly That thou, Iago, who hast had my purse As if the strings were thine, shouldst know of this.

Shakspeare.

TUSSILAGO, colt's foot, in botany, a genus of plants, belonging to the class syngenesia, and order of polygamia superflua; and in the natural system ranging under the forty-ninth order, composite. The receptacle is naked; the pappus simple; the scales of the calyx equal, of the same height as the disk, and somewhat membraThere are twelve species; three of naceous. which are indigenous in Britain. TUS'SUCK, n. s. Diminutive of tuzz. A tuft of grass or twigs.

The first is remarkable for the several tussucks or

bunches of thorns, wherewith it is armed round.

Grew.

TUT, interj. The same with tush. A particle noting contempt.

Tut, tut! grace me no grace, nor uncle me no uncle. Shakspeare.

Tut, tut! here's a mannerly forbearance. TUTANA, or TOTANA, a considerable town of the province of Murcia, Spain, on the great road by which that province communicates with Andalusia. It contains 8000 inhabitants; the houses are low and mean; and the public buildings confined to a church, a monastery, and an hospital. The surrounding country is naturally fertile, but in a great measure uncultivated, the inhabitants being thinly scattered and devoid of activity. Eighteen miles E. N. E. of Lorca.

TU'TANAG, n. s. Chin. tutunage. Spelter. Tutanage is the Chinese name for spelter, which we erroneously apply to the metal of which canisters are made, that are brought over with the tea from China; it being a coarse pewter made with the lead carried from England, and tin got in the kingdom of Quintang.

Woodward.

TUTENAG. This name is given in India to the metal zinc. It is sometimes applied to denote a white metallic compound, brought from China, called also Chinese copper, the art of making which is not known in Europe. It is very tough, strong, malleable, may be easily cast, hammered, and polished; and the better kinds of it, when well manufactured, are very white, and not more disposed to tarnish than silver is. Three ingredients of this compound may be discovered by analysis; namely, copper, zinc, and iron. Some of the Chinese white copper is said to be merely copper and arsenic.

TUTENAGO, an ore of zinc, containing commonly from sixty to ninety per cent. of zinc, the remainder iron, and a small proportion of clay. See MINERALOGY.