applied with a brush to the surface of a pad or cushion formed of flannel covered with floor-cloth; the block, held by a handle at the back, is placed face downwards on this cushion, and the layer of paint thus obtained is transferred to the surface of the canvas by pressing the block smartly down on the latter. A second impression is made in a similar way by the side of, and close to, the first; and so on throughout the length and breadth of the canvas; each impression being about 15 inches square. The proper junction, or register, of the successive impressions is aided by pins at the corners of the blocks. When the whole surface is thus printed with one colour, all the other three are similarly applied in succession. Such would likewise be the case if the number of colours was more than four; but the greater the number the greater would be the care necessary in adjusting the numerous partial impressions so as to ensure a proper arrangement of the whole.

In printing floor-cloth for passages and stairs, where the width seldom exceeds a yard, the canvas is prepared in the frames as in other cases; but it is cut up into strips before being printed, and has usually a border given to its pattern by means of blocks much narrower than those employed in other cases. Where there are large patches of one colour in the pattern of floor-cloth, they are not given by smooth surfaces on the block, but by means of little projecting squares technically called teeth; the reason for this is, that if a surface two or more inches square were laid on wet paint, it would not take up the paint equally, but would exhibit it in an unequal splat; whereas, if the surface were broken up into a number of smaller surfaces by means of lines cut in various directions, these lines would act as airvents, and the paint would be taken up pretty equally by the little squares or teeth. One among the features which distinguish cheap oil-cloth (so-called) from good, is the hastiness with which the processes are conducted; the paint has often insufficient time for drying, and is sold for use before it is fitted to bear the friction of the feet. It has been suggested, with some probability, that floor-cloth, especially when thus insufficiently dried, may tend to rot the boards of a flooring in a damp room, by preventing the free escape of vapour.

Mr. Loudon (Encyclop. of Cottage and Villa Architecture,' p. 345) notices a suggestion for the use of paper instead of floor-cloth or carpet. The carpet, according to this suggestion, is formed in the first instance of any fragmentary pieces of linen, cotton, canvas, or other material, sewn up to the required size. This cloth is stretched on the floor of a large room, and kept down in its place by being pasted round the edges. On this foundation stout paper is pasted; two thicknesses being applied in every part, with the joints so arranged as to be but little perceptible. On this a surface of wall paper is pasted; and here an opportunity for the exercise of taste is afforded, since a variety of pleasing patterns may be obtained by the judicious combination of fragments which are in themselves of very little account. When the pattern is thus far produced, it is coated twice with warm melted size, applied so as to soak into every part of the paper, and to prepare it for the reception of the varnish. One or more coatings of boiled linseed oil are applied after the size, and to the oil succeeds copal varnish. Of the floor-covering so produced it is said, "these carpets are portable, and will roll up with about the same ease as oil-cloth; they are very durable, are easily cleaned, and if made of well-chosen patterns have a very handsome appearance. Where labour is cheap the cost will be very trifling; the materials being of little value, and the expense consisting chiefly in the time requisite to put them together. Where cloth cannot be easily procured, the carpet may be made by pasting paper to painted boards; when by repeated coats of paper it has become strong and firm, it will separate from the paint and will be as durable as if mounted on any kind of cloth. For earth, brick, or stone floors, in order to render them impervious to damp, these carpets may be made with two faces, by pasting paper on both sides of the cloth which forms their basis, aud well oiling or varnishing them on the under as well as the upper surface; they may also be bound with leather or any strong substance, to prevent moisture from penetrating to the paste.

It has also been more than once suggested, that 'Geographical carpets' might advantageously be constructed for school-rooms and similar apartments. By this term is meant the employment of a carpet or covering in which the lines of a map are substituted for a regular pattern. There would, as Mr. Loudon has stated, be a good deal of difficulty in working out the idea, since it would have to be decided whether the map should be printed before being laid down as a carpet, or filled in by hand afterwards. The choice of material too, whether linen, holland, or paper, would be attended with some difficulty; but such a map, especially if the northern portion of it were directed to the northern side of the room, would not be without its value in rendering the position of a country or district familiar to the inmates of the room.

Messrs. Goodyear have recently patented a new kind of floor-covering, intended to combine at once the qualities of durability, softness, elasticity, and cheapness. Carpets are expensive, and not adapted for halls or public rooms; floor-cloth is wanting in softness and elasticity. It was to meet this want that the substance called Kamptulicon was invented some years ago. Many persons consider, however, that the kamptulicon, often used for the floors of churches and other large

buildings, has a tendency to become brittle after some time of usage. Be this as it may, Messrs. Goodyear have devised a mode of combining cork, cotton, wool, and other fibrous materials, with india-rubber, and spreading the mixture upon a back or ground of canvas or woollen. In this state, the carpet or floor-covering undergoes a kind of embossing process, plain or in colours. When thoroughly dried, it is said to have the elasticity and noiselessness of a velvet pile carpet, in addition to much durability.

FLOORS. The platforms which form the separate stories of a building are habitually known by the name of Floors, and they are generally composed of the ceiling, the joists, and the floorboards; great varieties of construction are, however, admitted in each of these details. The various modes of executing ceilings will be discussed under PLASTERER'S WORK, and attention will in this article only be called to the parts of floors which come exclusively within the attributions of the carpenter and joiner.

Floors are either simple, or single-joisted floors; or framed floors. In the former, the ceiling and floor-boards are attached directly to the joists, which are made strong enough to carry the weight likely to be brought upon them, without any intermediate support. In the framed floors, a more complicated system of construction is adopted, for girders are introduced to divide the bearing, and to them are attached, as the case may be, binding-joists, bridging-joists, and ceiling-joists; the two latter of which respectively carry the floor-boards and the ceiling. It is usually considered that a single-joisted floor is, in proportion to the cubical quantity of wood it contains, stronger than a framed floor; but, as Tredgold very properly remarks, when the bearing of the joists becomes considerable, the ceilings of single-joisted floors are liable to be affected by the natural movements of the timber; and at all times it is easier to execute the works required to prevent the transmission of sound in a framed, than it is in a single-joisted, floor. [SOUND BOARDS.]

The weight a floor may have to carry must of course depend upon the purposes it is intended to fulfil. In house floors it is very rarely indeed that a greater weight than 45 lbs. per foot, superficial, can be applied, whilst in common shop and assembly-room floors, it is advisable to count upon a load equal to 80lbs. per foot, superficial, and in bridges, upon a weight of 200 lbs. per foot; if corn or grain should be stacked upon a floor, it is even desirable to calculate upon a load of 250 lbs, on the superficial foot. Upon these data the strength of the b d2 timbers of floor may be calculated by the formula w == Tc; in which w = twice the breaking weight in lbs., distributed over the whole length, or the breaking weight applied at the centre; b the breadth in inches; d the depth also in inches; the clear length of the bearing in feet; and e the coefficient of strength of the various descriptions of wood. Tredgold gives, in his Elementary Principles of Carpentry,' some more general empirical formula for calculating the dimensions of the various details of house floors; and as they are perfectly safe, nay, rather in excess of the absolute requirements of the by practical builders. The scantlings of girders he calculates from the cases they are designed to meet, they may be unhesitatingly adopted formula (No. 1.) b

=

7472

d

=

4012

; in which b the breadth, and d, the depth in inches, and l the length, in feet, between the bearings. The scantlings of binders he calculates by formula (No. 2.), b in which the same numeration is preserved. The scantlings of single joists he calculates by formula (No. 3.), d

ceiling-joists by the formula (No. 4.), d

=

2.2

(1)

647

b 3

=

d3;

and those of

Tables calculated upon

these formulæ are given in the body of the work above-quoted, pages 261 to 264.

Practically the limit for the bearings of single-joisted floors seems to be fixed at from 20 to 24 feet; for although it is possible to obtain timbers deep enough to carry the loads of floors of larger spans, yet the depth becomes so considerable as to render the use of double floors preferable, even without reference to the danger and inconvenience arising from the shrinking, or warping, of the joists. The latter inconvenience may be obviated, by the introduction of a system which is now very general in London, known by the name of herring-bone strutting, in which the joists are kept in their places by means of cross-struts nailed at the sides of the joists, whose rigidity and steadiness are thus greatly increased. Another practical observation is to be made with respect to single joists, namely, that they must be wide enough to afford a good hold to the floor brads; perhaps a minimum width equal to one and a half times the thickness of the floor boards used upon them may be admitted.

A span of more than 24 feet in a double floor can rarely be accomplished with ordinary timber girders; and it therefore becomes necessary to resort to the use of Trussed, or of Cast Iron, or of Wrought Iron, Girders. Of late years the latter are almost exclusively used, on account of their greater elasticity, and of their giving considerable

notice of their possible weakness. Cast iron, in fact, breaks suddenly under an excessive load, without warning; wrought iron yields gradually. The rules for calculating the strength of metal girders will be found under the head of GIRDERS; they have been derived from the researches of Tredgold, Fairbairn, Barlow, and Hodgkinson. In France, much attention is paid to the construction of a species of fire-proof floors, in which a framework of H rails, with smaller split rod intermediate bars is formed, and the spaces are filled in with the very energetic plaster obtained by the calcination of the gypsum of the Paris basin. On the top of this artificial landing, sleeper-joists are bedded, and the floor boards are nailed to them, in the better classes of rooms; whilst in the offices, or in the attics, the tiled floors are at once bedded on the joists and filling-in materials. This kind of floor has been imitated in England, and the plaster has been replaced by cement concrete; the principle of construction remaining the same, namely, the formation of an artificial landing, bearing upon the external walls. There are great advantages in these systems of fire-proof floors; but it is to be observed that they load the walls to a dangerous extent, and that in many cases the plaster, or the concrete used, exercises a powerful lateral thrust upon the walls.

The flooring itself is, in England, usually executed of white or yellow deals, or battens; in France, it is almost invariably executed of wainscot, in narrow widths, laid either with a straight joint, or in herring-bone fashion; in Holland and Germany, the ordinary practice is to use wide timber slabs, which shrink and crack in a very disagreeable manner. The boards are usually grooved and feather-tongued, or edge-nailed, in the best descriptions of work; and occasionally, when it is desired to introduce ornamental decoration in the floors, a second layer, composed of variously coloured woods is laid upon a coarser sublayer; the upper layer is usually known under the name of Parquet flooring. The thickness of the single floor boards, or battens, in England, is usually made to range between 1 and 14 inches; but the batten floors are rarely more than 14inch thick.

FLO'RA, in the Roman mythology, was the goddess of spring and of flowers, and the wife of Zephyr. A flamen was appointed to her service by Numa. Her temple stood near the Circus Maximus. The Floralia were festivals celebrated in honour of Flora, from the 28th of April to the 2nd of May. Instead of the fights of wild beasts, hares and rabbits were exhibited and chased about on those occasions; and women of loose character performed dances and mimic fights, throwing beans and chick-pease among the crowd. The Ædiles presided at these games. (Cicero In Verrem,' v. 14.) The ground on which the games were performed is still called Campo di Fiora; it forms one of the squares of modern Rome, and serves as a market-place. Some pretend that the Flora who bequeathed this ground to the Roman people was a mistress of Pompey, the remains of whose theatre are close by. But the floral games were instituted long before Pompey, at the beginning of the 6th century of Rome. They were no doubt originally annual games of the country people. The festival was discontinued for awhile, but was restored in B.C. 173, in consequence of the blossoms of the fruit trees having in that year been severely injured by storms. As long as they were held, the floralia were scenes of the most extravagant licentiousness. The May games and floral games of the middle ages were the direct descendants of the Roman floralia. The term ("jeux floraux") was applied to the more refined poetical assemblies and competition for prizes held at Toulouse. [CLEMENCE ISAURE, in BIOG. DIV.]

FLORIN. [MONEY.]

FLOTSAM, is such portion of the wreck of a ship and the cargo as continues floating in the water. Jetsam is where goods are cast into the sea, and there sink and remain under water; and ligan is where they are sunk in the sea, but are tied to a cork or buoy, in order that they may be found again.

These barbarous and uncouth appellations are used to distinguish goods in these circumstances from legal wreck, in order to constitute which they must come to land.

Flotsam, jetsam, and ligan belong to the crown if no owner appears to claim within a year after they are taken possession of by the persons otherwise entitled. They are accounted so far distinct from legal wreck, that by the king's grant of wreck, flotsam, jetsam, and ligan will not pass.

Wreck has been frequently granted to lords of manors as a royal franchise; but if the king's goods are wrecked, he can claim them at any time, even after a year and a day.

FLOUR; FLOUR-MILLS. Under the heading WINDMILL will be found an account of the mechanism of the windmills employed in grinding flour, raising water, &c., chiefly in the days when the steamengine had not yet come much into use, or in districts where steampower is not readily available. Referring to that article for a description of the ordinary mode of producing flour, we shall here treat briefly of certain modern improvements, either in the substitution of steampower for wind-power, or in the adoption of new forms of grindstone. In the ordinary mode of grinding wheat into flour, or any other grain into meal (flour being only one kind of meal) there are circular stones employed, each about 4 feet in diameter; they are flat discs, placed one upon another. The lower one is fixed, while the upper one revolves horizontally on a vertical axis, with a speed of 100 to 120 revolutions per minute. The surfaces are channelled or grooved, to

increase their frictional effect; and they are placed so nearly in contact that grains of corn between them are crushed to powder. Now it is found that, owing to the weight (often 14 cwt.), size, and velocity of the upper stone, the flour is much heated before it can escape from the edge of the two stones; it is overground, and is apt to clog into lumps. Millers and millwrights have long sought for a cure for this evil. Some have tried to vary the shape of the grinding surfaces of the stones; while others have sought rather to direct a cold blast of air between them, in order to keep the grain and the flour cool, to separate the grains, to allow all to be acted on equally, and to prevent clogging and pastiness. To insure some or other of these results has been the main object of numerous inventions by Corcoran, Gordon, Taylor, Bovill, Pinel, M'Lellan, Banks, Goodier, Westrupp, Spiller, Valck, Seeley, Schiele, Harwood, White, and others. To notice briefly a few plans is all that need be attempted here.

Bovill's invention comprises five different elements: a mode of driving two ranges of millstones from a central horizontal shaft by means of half-crossed straps, which pass from the horizontal shaft to riggers or pulleys on the vertical spindles of the ranges of millstones; an arrangement for drying meal and flour by means of steam and hot air, instead of kiln-drying the grain previous to grinding; a inode of applying steam to give moisture to manufactured flour, which, after grinding, is in too dry a state; an arrangement for washing grain to separate its impurities, and then drying by currents of hot air; and lastly, a mode of employing machinery in combination with millstones, having apertures covered with wire-gauze or other perforated material, in order to facilitate the passing away of the ground flour through the apertures. All these parts combine to produce a very efficient grinding apparatus.

White's apparatus comprises several new principles. While the upper stone is revolving, the rhyne or connecting piece between the driving spindle and the stone is forced upon its upper side, in such manner as to serve for a rolling or crushing bed for the preparatory crushing rollers. Immediately over this rolling surface are placed the sinall crushing rollers, adjustable to distance by screws. The grain to be ground passes through a hopper upon the flat rolling surface driven round by the millstone spindle. The revolution of a flat disc rollingplate causes the two crushing rollers to turn upon their respective axes, and thus to crush the grain as it is fed between the rollers. As the grinding proceeds, the crushed grain falls off the rolling-plate, and reaches the surface of a distributing-plate. The top of this distributor is corrugated radially, to aid in the distribution of the grain. The distributor is made hollow, for the passage of cool air; it has four or five air-holes, which are horizontal curved passages; the outer ends of these holes terminate at the junction of the grinding surfaces, while the inner ends open into a central aperture in the distributor communicating with a descending trumpet-mouthed tube. Air enters by these trumpet-mouths, in consequence of the suction exerted by the chambered air-distributor; the current is strongest just where the grain is most severely acted on and requires most cooling, and then the air escapes by the five or six holes.

In Westrupp's conical mill, there is a conical revolving stone placed beneath a fixed stone. The upper stone is a cone, hollow beneath, and the lower one is a cone fitting into it; the two being susceptible of easy adjustment, according to the size and condition of the corn to be ground. On account of the conical form of the rubbing surfaces, the flour leaves the mill very easily. It grinds the corn more completely than an ordinary mill, leaving less farina in the bran; for the bran remains awhile after the flour is expelled, and then falls by gravity to another pair of stones, where the remaining farina is ground out of it. It has been asserted that this mill obtains one shilling's-worth more of flour from a quarter of corn than the ordinary mills, and that the flour is better in quality; but this is a statement requiring confirmation. Schiele's anti-friction corn-mill is an application to practical purposes of a peculiar curved surface, which Mr. Schiele discovered; or rather, a concave revolving surface rubbing against a convex fixed surface, to prevent a kind of irregular friction which results from the contact of conical surfaces. The gradual variation of the curvature, in relation to the increasing distance of the parts from the centre of motion, equalises the rubbing pressure. The wear upon the stones is uniform in all parts; and it is expected by the inventor that there will be no need to re-dress the stones until actually worn down many inches equally all

over.

M. Falguière, a Frenchman, has invented a mill comprising a pair of vertical stones revolving at high velocities; they weigh together less than 1 cwt., and are made small and portable for use in camps and ships. The grain is fed down from a hopper into a horizontal cast-iron pipe, with an Archimedean screw inside; the screw carries it to the other end of the pipe. The stones are fixed in a pair of frames, surrounded by a copper casing in two hinged halves. The running stone is carried upon a separate shaft driven by a band. The stones are concave at their travelling surfaces, and the grain is conveyed into this space from the tube.

The gruaux flour of M. D'Arblay attracts much attention on the continent of Europe, on account of the great extent to which the finest and most nutritious part of the flour is retained. Hard wheats of all kinds, especially Sicilian, Russian, and Sardinian, from the large per centage of gluten which they contain, are the best adapted for the

The resistance of bodies only partly immersed in fluids, and having a depth bearing a sensible ratio to that of the fluids, as in barges towed along canals, is subject to laws far different from those which we have considered, for the quantity immersed is itself a function of the velocity, diminishing considerably with great velocities: thus, notwithstanding the increase of resistance due to velocity, this diminution due to less immersion permits the possibility of a minimum resistance. This important subject will be further considered in the article HYDRAULICS.

The term fluid has been extended to the supposed media through which the forces of electricity, galvanism, and magnetism act, but little that can be relied upon has been deduced from their supposed analogy with material fluids. [ELECTRICITY.] A surer source of calculation is found in detecting the laws of their elementary actions by experiment; and indeed this process seems to point out the most feasible methods for discovering the molecular laws even of material fluids, manifested both in their tenacity and their capillary phenomena. Fluidity cannot be easily defined in the explicit terms of its exact causes until more is known of the true laws of the forces which govern the internal arrangement of bodies; but taking the effect, we may with Laplace say, that "mobility is the characteristic property of fluids." Hence fluidity may be rendered imperfect by the admixture of solids with fluids, as in mud, &c. The effects of fluidity become still more concealed in masses consisting of heterogeneous solids holding fluids in their pores, as in moist clays, dough, &c.; nor are they fully developed in solids which, through the action of heat, are tending to a fluid state, as in melting tallow, wax, glass, &c. In none of these cases can the laws of perfect fluids be applied; but as they belong only to states of transition, their peculiar laws do not deserve, or at least have not obtained, much consideration.

FLUIDITY. All ponderable matter exists either in the gaseous, fluid, or solid state; and most solids, when heat is applied to them, may be rendered fluid, or converted into liquids, under which circumstances mutual repulsion of particles takes the place of cohesion. The degree of heat required to produce this effect is different in different solids, but, cæteris paribus, it is always the same in the same solid: in many cases the transition from the solid to the fluid form is sudden, while in other instances solids pass through various degrees of liquidity before they become perfectly fluid. Of the first mode of becoming fluid ice and the metals are examples, and wax or tallow of the second.

As most solid bodies may be rendered fluid by heat, so many gaseous and fluid bodies are converted into solids by diminishing their temperature. Solid bodies in becoming fluid render latent a large quantity of heat; and on the other hand, fluid bodies in becoming solid evolve much sensible heat. The heat which is requisite to the fluid existence of a body is termed the heat of fluidity. These facts are proved by two simple experiments. Mix a pound of water at 32° Fahr. with a pound of water at 172°, and the resulting temperature will be the mean, or 102°. If a pound of ice at 32° be dissolved in a pound of water at 172°, the solution will not have the mean temperature of 102°, but only 32°. As, then, the pound of ice, by being rendered merely fluid, absorbs 140° of heat, so the quantity of heat which becomes sensible when a pound of water at 32° is converted into ice at 32° amounts also to 140°. The actual quantity of heat rendered latent by different fluids as they liquify depends upon the nature of the substance; thus, according to Person, the under-mentioned bodies contain the annexed quantities of heat in the latent state when rendered fluid :

Almost all gases are invisible; but several which are so when they exist alone, become visible on being mixed with one another. Thus, binoxide of nitrogen being mixed with atmospheric air, the combination becomes visible and of a red colour. Several gases also become visible when mixed with aqueous vapour. An augmentation of the temperature of vapour may, by producing an increased rarefaction, render it invisible; and, on the other hand, a diminution of temperature will cause such a condensation as may render visible a vapour which before was imperceptible. These effects of heat and cold upon vapour have been proposed as explanations of the apparent diminution of the mass of a comet when near the sun, and of its apparent enlargement in receding from that luminary. All elastic fluids are transparent, but different quantities of light are absorbed in passing through those of different kinds, and when the thickness of a stratum of fluid is con- . siderable, the absorption is so great as to render an object beyond it invisible. The elastic forces of a dry gas at a given temperature are inversely proportional to the volumes they occupy; and this law holds good also both for mixtures of elastic vapours with each other, and of vapours with gases, provided no chemical action takes place between them. Thus, different fluids of equal temperatures and equal elastic forces being introduced together in a close vessel whose capacity is equal to the sum of the volumes of the fluids separately, the fluids for a time remain separately in equilibrio; but experience shows, that gradually the fluids intermingle with one another, producing a homogeneous fluid preserving the same temperature and elastic force. It has been found also that if different fluids having equal temperatures with different elastic forces, and occupying separately equal volumes v, be mixed together in a close vessel whose capacity is v, the elastic force of the mixed fluid will be equal to the sum of the elastic forces of the separate fluids, and the temperature will remain constant. When a vapour at a given temperature is compressed by being confined within a smaller space than that which it previously occupied, part of the vapour becomes condensed, and the remainder continues to possess the elastic force due to the temperature. And again, if the volume of a quantity of vapour be increased, the vapour will expand, and, if not in contact with the liquid from which it was produced, its elastic force will be diminished; if in contact with the liquid new vapour will rise to supply the void created by the dilatation, and the elastic force will remain constant.

The temperatures at which liquids become elastic fluids by the action of caloric are very various; hydrochloric and nitric ethers boil, under the usual pressure of the atmosphere, the one at 51.9°, and the other at 185°; acetic ether boils at 165°; water boils at 212°; while mercury can be made to boil only at a temperature of 662°.

The quantity of vapour produced by heat from a liquid increases with an increase of temperature, and while in contact with the liquid its elasticity varies with its specific gravity. The elastic force of vapour is increased when the vapour is mixed with air; for if the interior of a barometer tube be moistened at the upper end with water, and air be introduced in it above the column of mercury, the tube being inserted as usual in a cistern of the latter fluid, the depression of the mercurial column in the tube by the expansion of the vapour and air, in consequence of an application of heat on the exterior, is greater than that which results from the expansion of air when dry.

The atmosphere which surrounds the earth is endowed with an elastic power; and partaking, moreover, of the earth's diurnal rotation, its particles should, by their elasticity and centrifugal force combined, recede from the earth till the whole is dissipated in space. Such is not the fact; and hence it is inferred, either that at a certain elevation above the surface of the earth the elasticity of the atmosphere is totally destroyed by the absence of caloric; or that beyond the stratum in which the centrifugal force of the particles is equal to their gravitation, there may exist, in a state of rest, an ethereal fluid occupying the whole extent of space, and preventing the atmosphere from being further expanded by its own elasticity.

Now, by mechanics, it may be found, that the distance from the surface of the earth to the stratum of the atmosphere in which the centrifugal force of the particles is equal to their gravity is about five