when the thickness is one of the terms of the series 2, 4, 6, 8, &c. See OPTICS.

FIXED AIR. See CARBONIC acid gas.

FIXED stars. See STAR.

FLAG is more particularly used at sea; for the colours, ancients, standards, &c. borne on the tops of the masts of vessels, to notify the person who commands the ship, of what nation it is, and whether it be equipped for war or trade. The admiral in chief carries his flag on the main-top; the viceadmiral on the fore-top; and the rear-admiral on the mizzen-top. When a council of war is to be held at sea, if it be on board the admiral, they hang a flag in the main-shrouds; if in the vice-admiral, in fore-shrouds; and if in the rear-admiral, in the mizzen-shrouds. Besides the national flag, merchant-ships frequently bear lesser flags on the mizen-mast, with the arms of the city where the master ordinarily resides; and on the fore-mast, with the arms of the place where the person who freights them lives.

FLAG, to lower or strike the, is to pull it down upon the cap, or to take it in, out of the respect, or submission, due from all ships or fleets inferior to those any way justly their superiors. To lower or strike the flag in an engagement is a sign of yielding. The way of leading a ship in triumph is to tie the flags to the shrouds, or the gallery, in the hind part of the ship, and let them hạng down to, wards the water, and to tow the vessels by the stern. Livy relates, that this was the way the Romans used those of Carthage.

FLAG, to hang out the white, is to ask quarter; or it shows when a vessel is arrived on a coast, that

it has no hostile intention, but comes to trade, or the like. The red flag is a sign of defiance, and battle.

FLAG officers, those who command the several squadrons of a fleet; such are the admirals, viceadmirals, and rear-admirals. The flag-officers in our pay, are the admiral, vice-admiral, and rearadmiral, of the white, red, and blue. See ADMIRAL.

FLAG ship, a ship commanded by a general or flag-officer, who has a right to carry a flag, in contradistinction to the secondary vessels under the command thereof.

FLAGELLANTES, whippers, in church-history, certain enthusiasts in the thirteenth century, who maintained, that there was no remission of sins without flagellation, or whipping. Accordingly, they walked in procession, preceded by priests carrying the cross, and publicly lashed themselves, till the blood dropped from their naked backs.

FLAGEOLET, a little flute, used chiefly by shepherds, and country-people. It is made of box, or other hard wood, and sometimes of ivory, and has six holes besides that at the bottom, the mouthpiece, and that behind the neck. See the article FLUTE.

FLAIL, an instrument for thrashing corn. A flail consists of the following parts: 1. the hand-staff, or piece held in the thresher's hand; 2. the swiple, or that part which strikes out the corn; 3. the caplins, or strong double leathers, made fast to the tops of the hand-staff and swiple; 4. the middle band, being the leather thong, or fish-skin, that ties the caplins together.

FLAMBEAU, a kind of large taper, made of hempen

wicks, by pouring melted wax on their top, and letting it run down to the bottom. This done, they lay them to dry; after which, they roll them on a table, and join four of them together by means of a redhot iron; and then pour on more wax, till the flambeau is brought to the size required, Flambeaus are of different lengths, and made either of white or yellow wax.

FLAME. Simple ignition never exceeds in intensity of light the body by the contact of which it is produced; but flame consists of volatile inflammable matter, in the act of combustion, and combination, with the oxygen of the atmosphere. Many metallic substances are volatilized by heat, and burn with a flame, by contact of the air in this pure state. Sulphur in the act of inflammation is volatilized, and in that state it unites with the oxygen of the air, and forms SULPHURIC acid, which see.

FLAMEN, in Roman antiquity, the name of an order of priests, instituted by Romulus or Numa; authors not being agreed on this head.

FLANEL, or FLANNEL, a loose sort of woollen stuff, not crossed, and wove on a loom with two treddles, like baize.

FLATS, in music, a kind of additional notes, which, together with sharps, serve to remedy the defects of musical instruments, wherein temperament is required.

FLAX, See Linum.

FLEA, puler, in zoology, a genus of insects without wings, of a roundish, compressed figure; the legs are three pair, and formed for leaping: the eyes are two, and simple; the mouth is bent down

ward; the colour is a deep purple, approaching to black. The flea is an insect which infests birds, as well as quadrupeds, and lays eggs, called nits: these produce a kind of nympha, or white worms; which after some time are transformed, in the manner of caterpillars, into perfect fleas.

FLEECE, Order of the golden, an order of knighthood instituted by Philip II. duke of Burgundy. These knights at first were twenty-four, besides the duke himself, who reserved the nomination of six more: but Charles V. increased them to fifty.

He

gave the guardianship of this order to his son, Philip, king of Spain, since which the Spanish monarchs are chiefs of the order. The knights had three different mantles ordained them at the grand solemnity, the collar and fleece.

FLEECY Hosiery, a useful kind of manufacture in which fine fleeces of wool are interwoven into a cotton piece of the common stocking texture. Any thing manufactured in this way, has, on one side, the appearance of common hosiery, and on the other that of raw wool.

› FLEET, commonly implies a company of ships of war, belonging to any prince or state: but sometimes it denotes any number of trading ships, em. ployed in a particular branch of commerce. In sailing, a fleet of men of war usually divide into Sthree squadrons; the admiral's, the vice admiral's, and the rear admiral's squadron, all which being distinguished by their flags and pendants, are to put themselves, and, as near as may be, to keep themselves, in their customary places, viz. The admiral, with his squadron, to sail in the van, that so he may lead the way to all the rest in the day time, by the

sight of his flag in the main-top mast head; and in the night-time, by his lights or lanterns. The vice-admiral and his squadron, are to sail in the centre or middle of the fleet; the rear-admiral and the ships of his squadron, to bring up the rear. Sometimes, other divisions are made, and those composed of the lighter ships, and the best sailors, are placed as wings to the van, centre, and rear.

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Merchant-fleets generally take their denomination from the place they are bound to, as the Turkey-fleet," "East India-fleet." These, in times of peace, go in fleets for their mutual aid and assistance: in time of war, besides this security, they likewise procure convoys of men of war, either to escort them to the places whither they are bound, or only a part of the way, to a certain place or latitude.

FLEET-DITCH, a small stream, which, rising in the adjacent country, passing through Clerkenwell, and running under a market to which it gives name, empties itself into the Thames, on the right of Blackfriars-bridge, in London. The name "fleet" is not commonly accounted for; but it appears to originate in the flowing of the tide of the Thames into its mouth, a circumstance more particularly observable near that river, where alone the stream is so called. Fleta, from the Saxon fleot, signifies, in barbarous Latin, a place where the tide comes up.

FLEET-prison, a gaol to which persons are committed by the courts of chancery and commonpleas; or in which they are confined for debt. It has its name from a small stream, called Fleetditch, close to which it stands.