in Geometry, a quantity extended in length only, without any breadth or thickness. It is formed by the flux or motion of a point. See Fluxions, and Geometry.

**Line**, in the art of war, is understood of the disposition of an army ranged in order of battle, with the front extended as far as may be, that it may not be flanked.

**Line of Battle**, is also understood of the disposition of a fleet in the day of engagement; on which occasion the vessels are usually drawn up as much as possible in a straight line, as well to gain and keep the advantage of the wind as to run the same board. See Naval Tactics.

**Horizontal Line**, in Geography and Astronomy, a line drawn parallel to the horizon of any part of the earth.

**Equinoctial Line**, in Geography, is a great circle on the earth's surface, exactly at the distance of 90° from each of the poles, and of consequence bisecting the earth in that part. From this imaginary line, the degrees of longitude and latitude are counted.—In astronomy, the equinoctial line is that circle which the sun seems to describe round the earth on the days of the equinox in March and September. See Astronomy and Geography.

**Meridian Line**, is an imaginary circle drawn through the two poles of the earth and any part of its surface. See Geography Index.

**Ship of the Line**, a vessel large enough to be drawn up in the line, and to have a place in a seafight.

**Line**, in Genealogy, a series or succession of relations in various degrees, all descending from the same common father. See Descent.

**Line**, also denotes a French measure containing the 12th part of an inch, or the 144th part of a foot. Geometricians conceive the line subdivided into six points. The French line answers to the English barleycorn.

**Fishing Line**. See Fishing Line.

**Lines**, in Heraldry, the figures used in armories to divide the shield into different parts, and to compose different figures. These lines, according to their different forms and names, give denomination to the pieces or figures which they form, except the straight or plain lines. See Heraldry.

**Linea alba**, in Anatomy, the concourse of the tendons of the oblique and transverse muscles of the abdomen; dividing the abdomen in two, in the middle. It is called linea, line, as being straight; and alba, from its colour, which is white.—The linea alba receives a twig of a nerve from the intercostals in each of its digitation or indentings, which are visible to the eye, in lean persons especially.

**Lineament**, among painters, is used for the outlines of a face.

**Linear numbers**, in Mathematics, such as have relation to length only; such is a number which represents one side of a plain figure. If the plain figure be a square, the linear figure is called a root.

**Linear Problem**; that which may be solved geometrically by the intersection of two right lines. This is called a simple problem, and is capable but of one solution.

**Linens**, in commerce, a well known kind of cloth, chiefly made of flax.—Linens was not worn by the Jews, Greeks, or Romans, as any part of their ordinary dress. Under-tunics of a finer texture supplied the place of shirts: Hence the occasion for frequent bathing. Alexander Severus was the first emperor who wore a shirt: but the use of so necessary a garment did not become common till long after him.

The linen manufacture was probably introduced into Britain with the first settlement of the Romans. The flax was certainly first planted by that nation in the British soil. The plant itself indeed appears to have been originally a native of the east. The woollen-drapery would naturally be prior in its origin to the linen; and the fibrous plants from which the threads of the latter are produced, seem to have been first noticed and worked by the inhabitants of Egypt. In Egypt, indeed, the linen manufacture appears to have been very early: for even in Joseph's time it had risen to a considerable height. From the Egyptians the knowledge of it proceeded probably to the Greeks, and from them to the Romans. Even at this day the flax is imported among us from the eastern nations; the western kind being merely a degenerate species of it.

In order to succeed in the linen manufacture, one set of people should be confined to the ploughing and preparing the soil, sowing and covering the seed, to the weeding, pulling, rippling, and taking care of the new seed, and watering and dressing the flax till it is lodged at home: others should be concerned in the drying, breaking, scutching, and heckling the flax, to fit it for the spinners; and others in spinning and reeling it, to fit it for the weaver: others should be concerned in taking due care of the weaving, bleaching, beating, and finishing the cloth for the market. It is reasonable to believe, that if these several branches of the manufacture were carried on by distinct dealers in Scotland and Ireland, where our home-made linens are manufactured, the several parts would be better executed, and the whole would be afforded cheaper, and with greater profit.

**Staining of Linen**. Linen receives a black colour with much more difficulty than woollen or cotton. The black struck on linen with common vitriol and galls, or logwood, is very perishable, and soon washes out.—Instead of the vitriol, a solution of iron in sour strong beer is to be made use of. This is well known to all the calico-printers; and by the use of this, which they call their iron-liquor, and madder root, are the blacks and purples made which we see on the common printed linens. The method of making this iron liquor is as follows: A quantity of iron is put into the sour strong beer; and, to promote the dissolution of the metal, the whole is occasionally well stirred, the liquor occasionally drawn off, and the rest beat from the iron, after which the liquor is poured on again. A length of time is required to make the impregnation perfect; the solution being reckoned unfit for use till it has stood at least a twelves month. This solution stains the linen of a yellow, and different shades of buff-colour; and is the only known substance by which these colours can be fixed in linen. The cloth stained deep with the iron-liquor, and afterwards boiled with madder, without any other addition, becomes of the dark colour which we see on printed linens and cottons; which, if not a perfect black, has a very near resemblance to it. Others are stained paler with the same liquor diluted with water, and come out purple.

Linens may also be stained of a durable purple by means of solution of gold in aqua regia. The solution for this purpose should be as fully saturated as possible; it should be diluted with three times its quantity of water; and if the colour is required deep, the piece, when dry, must be repeatedly moistened with it. The colour does not take place till a considerable time, sometimes several days, after the liquor has been applied: to hasten its appearance, the subject should be exposed to the sun and free air, and occasionally removed to a moist place, or moistened with water.—When solution of gold in aqua regia is soaked up in linen cloths, the metal may be recovered by drying and burning them.

Linens flowered with Gold-leaf. Dr Lewis mentions a manufacture established in London for embellishing linen with flowers and ornaments of gold-leaf. The linen, he says, looks whiter than most of the printed linens; the gold is extremely beautiful, and bears washing well. The doctor informs us, that he had seen a piece which he was credibly informed had been washed three or four times, with only the same precautions which are used for the finer printed linens; and on which the gold continued entire, and of great beauty. Concerning the process used in this manufacture, he gives us no particulars.

Fossil Linen, is a kind of amianthus, which consists of flexible, parallel, soft fibres, and which has been celebrated for the use to which it has been applied, of being woven, and forming an incumbrable cloth. Paper also, and wicks for lamps, have been made of it. See Amianthus, Asbestos, and Mineralogy Index.