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with great liveliness and activity, no sooner come and some a combination of many, particularly Pan's within the influence of the acid particles, than they syringa, which consisted of seven reeds joined tospread themselves, and tumble down to all appear-gether sidewise. ance dead. The like may be done by a solution of salt, only with this difference; that by the application of this latter, they seem to grow vertiginous, turning round and round till they fall down. Tincture of salt of tartar used in the same manner kills them still more readily; yet not so, but there will be apparent marks of their being sick first and convulsed. Inks destroy them as fast as spirit of vitriol, and human blood, by virtue of the salt contained in it, produces the same effect. Urine, sack, and sugar, do all destroy them, though not so fast; besides, that there is some diversity in their figures and appearances, as they receive their deaths from this poison or that. The point of a pin dipped in spittle presently killed all the kinds of animalcules in puddle-water, as Dr. Harris supposes it will other animalcules of this kind.

GERMAN FLUTE. An instrument entirely differeut from the common flute. It is not, like that, put into the mouth to be played ; but the end is stopped with a tampion, or plug; and the lower lip is applied to a hole about two inches and a half, or three inches, distant from the end. This instrument is usually about a foot and a half long; rather bigger at the upper end, than the lower; and perforated with holes, besides that for the mouth, the lowest of which is stopped and opened by the little finger's pressing on a brass, or sometimes a silver key, like those in hautboys, bassoons, &c. Its sound is exceedingly sweet and agreeable, and serves as a treble in a concert.

FLUTES, or FLUTINGS. In Architecture, perpendicular channels, or cavities, cut along the shaft of a column, or pilaster. They are chiefly effected in the Ionic order, where they had their first rise; though, indeed, they are used in all the richer orders, as the Corinthian and composite; but seldom in the Doric, and scarcely ever in the Tuscan.

We find in the waters of our ditches many species of small animalcules, both of the crustaceous and testaceous kinds. The legs of the creatures are short, they resemble those of crabs and lobsters, but are of a much more curious structure; they are less than a small flea, but they seem all breeders, carrying spawn at their tails, or in two small Each column has twenty-four flutes; and each bags, one hanging from each side. These bags are flute is hollowed in, exactly a quadrant of a circle: often seen broken, and the spawn is then found to but the Doric has but twenty. Between the flutes consist of globules very large in proportion to the are little spaces that separate them, which Vitruvius size of the creature. There is another sort besides calls stria, and we, lists: though, in the Doric, the these, as beautiful, but much smaller than they; flutes are frequently made to join to one another, this in shape more resembles the shrimp, and car-without any intermediate space at all; the list being ries its spawn as the shrimp does. These kinds sharpened off to a thin edge, which forms a part both seem only to have one eye, and that placed of each flute. exactly in the middle of the forehead, without the least trace of a dividing line; and they are often so transparent, that the motion of their bowels, and pulsation of their heart, may be seen.

FLUOR SPAR. Vitreous spar. Sparry fluor. A species of salt, which abounds in nature, formed by the combination of the sparry acid with lime. It is called spar, because it has the sparry form and fracture; fluor, because it melts very readily; and vitreous, because it has the appearance of glass, and may be fused into glass of no contemptible appearance.

FLUORIC ACID. A gaseous substance procured from fluor spar, which is of a corroding nature, and will dissolve glass, for which reason it has been used for etching on glass. This acid gas readily combines with water; and when dropped in, a hissing noise is produced with much heat.

FLUTE. An instrument of music, the simplest of all those of the wind kind. It is played on by blowing it with the mouth; and the tones or notes are changed by stopping and opening the holes disposed for that purpose along its side. The ancient fistulæ, or flutes, were made of reeds, afterwards of wood, and, lastly, of metal: but how they were blown, whether as our flutes, or as hautboys, does not appear.

It is plain, some had holes, which, at first, were but few, but afterwards increased to a great number; and some had none: some had single pipes,

FLUX. A general term made use of to denote any substance or mixture added to assist the fusion of minerals. In the large way, limestone and fusible spar are used as fluxes. The fluxes made use of in assays, or philosophical, experiments, consist usually of alkalies, which render the earthy mixtures fusible, by converting them into glass; or else glass itself in powder.

FLUXION. In Mathematics, denotes the velocity by which the fluents or flowing quantities increase or decrease; and may be considered as positive or negative, according as it relates to an increment or decrement.

The doctrine of fluxions, first invented by Sir Isaac Newton, is of great use in the investigation of curves, and in the discovery of the quadratures of curvilinear spaces, and their rectifications. In this method, magnitudes are conceived to be generated by motion, and the velocity of the generating motion is the fluxion of the magnitude. Thus, the velocity of the point that describes a line, is its fluxion, and measures its increase or decrease. When the motion of this point is uniform, its fluxion or velocity is constant, and may be measured by the space described in a given time, but when the motion varies, the fluxion of velocity at any given point is measured by the space that would be described in a given time, if the motion was to be continued uniformly from that term.

FLYING. The progressive motion of a bird,

or other winged animal in the air. The parts of birds chiefly concerned in flying are the wings and the tail; by the former, the bird sustains and wafts himself along; and, by the latter, he is assisted in ascending and descending, to keep his body poised and upright, and to obviate the vascillations thereof. It is by the largeness and strength of the pectoral muscles, that birds are so well disposed for quick, strong, and continued flying. These muscles, which in men are scarcely a seventieth part of the muscles of the body, in birds, exceed and outweigh all the other muscles taken together. The tail, Messrs. Willoughby, Ray, and many others, imagined to be principally employed in steering and turn ing the body, as a rudder; but Borelli has shown that this is the least use of it. Its chief use is to assist the bird in its ascent and descent in the air, and to obviate the vascillations of the body and the wings; for, as to turning the body to this or to that side, it is performed by the wings and inclination of the body, and but very little by the help of the tail. The flying of a bird, in fact, is a very different thing from the rowing of a vessel. Birds do not vibrate their wings towards the tail, as oars are struck towards the stern, but waft them downwards; nor does the tail of the bird cut the air at right angles, as the rudder does the water; but is disposed horizontally, and preserves the same situation what way soever the bird turns. In effect, as a vessel is turned about on its centre of gravity to the right, by a brisk application of the oars to the left; so a bird, in beating the air with its right wing alone, towards the tail, will turn its fore part to the left. Thus pigeons, changing their course to the left, would labor it with their right wing, keeping the other almost at rest. Birds of a long neck, alter their course by the inclination of their head and neck, which altering the course of gravity, the bird will proceed in a new direction. The act of flying is thus performed: the bird first bends his legs, and springs with a violent leap from the ground; then opens and expands the joints of his wings, so as to make a right line perpendicular to the sides of his body: thus the wings, with all the feathers therein, constitute one continued lamina. Being now raised a little above the horizon, and vibrating the wings with great force or velocity perpendicularly against the subject air, that fluid resists those succussions, both from its natural inactivity and elasticity, by means of which the whole body of the bird is protruded. The resistance the air inakes to the withdrawing of the wings, and consequently the progress of the bird, will be so much the greater, as the stroke of the fan of the wing is longer; but, as the force of the wing is continually diminished by this resistance, when the two forces continue to be in equilibrio, the bird will remain suspended in the same place; for the bird only ascends so long as the arch of air the wing describes, makes a resistance greater than the excess of the specific gravity of the bird above the air. If the air, therefore, be so rare as to give way with the same velocity as it is struck withal, there will be no resistance, and consequently the bird can never mount. Birds never fly upwards in a perpendicular line, but always in a parabola. In a direct ascent, the natural and artificial tendency would oppose and destroy each other, so that the

progress would be very slow. In a direct descent they would aid one another, so that the fall would be too precipitate.

FLYING, ARTIFICIAL. That attempted by men, by the assistance of mechanics. The art of flying has been attempted by several persons in all ages. The Leucadians, out of superstition, are reported to have had a custom of precipitating a man from a high cliff into the sea; first fixing feathers, variously expanded, round his body, in order to break the fall. Friar Bacon not only affirms the art of flying possible, but assures us, that he himself knew how to make an engine, wherein a man sitting, might convey himself through the air like a bird; and further adds, that there was then one who had tried it with success. The secret consisted in a couple of large thin hollow copper globes, exhausted of air, which, being much lighter than air, would sustain a chair whereon a person might sit. Father Francisco Lana, in his Prodromo, proposes the same thing as his own thought. He computes that a vessel of brass, fourteen feet in diameter, weighing three ounces the square foot, will only weigh one thousand eight hundred and forty-eight ounces, whereas a quantity of air, of the same bulk, will weigh two thousand one hundred and fifty-five ounces and two-thirds, so that the globe will not only be sustained in the air, but will carry with it a weight of three hundred and seventy-three ounces and two-thirds; and by increasing the bulk of the globe, without increasing the thickness of the metal, he adds, a vessel might be made to carry a much greater weight. But a globe of the dimensions he describes, Dr. Hook shows, would not sustain the pressure of the air, but be crushed inwards. Besides, in whatever ratio the bulk of the globe were increased, in the same must the thickness of the metal, and consequently the weight be increased; so that there would be no advantage in such augmentation.

FLYING DRAGON. A four-footed reptile of the lizard tribe, inhabiting Africa and India, which has a lateral membrane serving as a wing.

FLYING-FISH. A species of fish, common in the Mediterranean and Atlantic seas, with very large fins, by which they are enabled to spring from two hundred to three hundred feet, or until their fins become dry.

FOCUS. In Optics, is a point wherein several rays concur or are collected, after having undergone either refraction or reflection. This point is thus denominated, because, the rays being here brought together and united, their joint effect is sufficient to burn bodies exposed to their action; and hence this point is called the focus, or burning point. It must be observed, however, that the focus is not, strictly speaking, a point; for the rays are not accurately collected into one and the same place or point, owing to the different nature and refrangibility of the rays of light, to the imperfections in the figure of the lens, and other similar impediments. The focus, therefore, is a small circle, which Huygens has demonstrated to be one eighth the thickness of the lens, when it is convex

on both sides; that is, it cannot be less than this, but, in imperfect glasses, it exceeds the above measure sometimes considerably.

FOG, or MIST. A meteor consisting of gross vapors, floating near the surface of the earth. Mists, according to Lord Bacon, are imperfect condensations of the air, consisting of a large proportion of the air, and a small one of the aqueous vapor; and these happen in the winter, about the change of the weather, from frost to thaw, or from thaw to frost; but in the summer, and the spring, from the expansion of the dew.

If the vapors, which are raised plentifully from the earth and waters, either by the solar or subterraneous heat, do, at their first entrance into the atmosphere, meet with cold enough to condense them to a considerable degree, their specific gravity is by that means increased; and so they will be stopped from ascending, and return back, either in form of dew, or drizzling rain; or remain suspended some time, in the form of fog. Vapors may be seen on the high grounds as well as the low, but more especially about marshy places. They are easily dissipated by the wind, as also by the heat of the sun. They continue longest in the lowest grounds, because these places contain most moisture, and are least exposed to the action of the wind.

Hence we may easily conceive, that fogs are only low clouds, or clouds in the lowest region of the air; as clouds are no other than fogs raised on high. When fogs stink, then the vapors are mixed with sulphureous exhalations, of which they smell. Objects viewed through fogs, appear larger, and more remote, than through the common air. Boyle observes, that, upon the coast of Coromandel, and the most maritime parts of the East Indies, there are, notwithstanding the heat of the climate, annual fogs so thick, as to occasion those of other nations, who reside there, and even the more tender part of the natives, to keep their houses close shut up.

perfection; bend this to a long convex, fasten it upon a half roll, and fix it to a bench or table; then take some chalk, washed as clean as possible, and filtered through a fine linen cloth, till it be as fine as you can make it; and having laid some thereof on the roll, and wetted the copper all over, lay your foils upon it, and, with a polishing-stone and the chalk, polish your foils till they are as bright as a looking-glass; after which, they must be dried, and laid up secure from dust.

FOLIO. The full size of paper as it comes from the manufacturer; also books printed on paper of that size.

The

FOLIATING OF LOOKING - GLASSES. spreading the plates over, after they are polished, with quicksilver, &c. in order to reflect the image. It is performed thus: a thin blotting paper is spread on the table, and sprinkled with fine chalk; and then a fine lamina or leaf of tin, called foil, is laid over the paper: upon this, mercury is poured, which is to be distributed equally over the leaf with a hare's foot, or cotton: over this is laid a clean paper, and over that the glass plate, which is pressed down with the right hand, and the paper drawn gently out with the left. This being done, the plate is covered with a thicker paper, and laden with a greater weight, that the superfluous mercury may be driven out, and the tin adhere more closely to the glass. When it is dried, the weight is removed, and the looking-glass is complete.

FOMENTATION. The application of heat, generally accompanied with moisture, to any part of the body, for medicinal purposes. Thus in swellings of a part, we foment it with chamomile flowers, boiled, and wrapped in flannel; or in spasms of the bowels we apply fomentations by means of cloths dipped in hot water. Sometimes clysters are given warm, and in large quantity, with a view of acting as an internal fomentation. Sometimes a more penetrating or stimulating substance is added to increase the power of the fomentation, as brandy, camphor, or ammonia.

FOIL. Among jewellers, a thin leaf of metal placed under a precious stone, in order to make it look transparent, and give it an agreeable different color, either deep or pale. Thus, if you want a stone to be of a pale color, put a foil of that color FOOD OF PLANTS. In Agriculture, and under it; or, if you would have it deep, lay a dark Vegetation, the various kinds of fine attenuated one under it. These foils are made either of cop- and elaborated materials which are absorbed from per, gold, or gold and silver together. The copper the surrounding atmosphere, or taken up from the foils are commonly known by the name of Nu- soil, in order to their nourishment and support. It remberg or German foils. They are prepared as seems not improbable but that many of the more follows: procure the thinnest copper plates you fluid and elastic matters of nature may contribute can get; beat these plates gently upon a well-pol-in this way. The more ancient writers were exished anvil, with a polished hammer, as thin as tremely anxious to ascertain the nature of the possible; and placing them between two iron plates, pabulum, or food of plants, but their inquiries on as thin as writing paper, heat them in the fire; then the subject were far from satisfactory. boil the foils in a pipkin, with equal quantities of The researches of Dr. Ingenhousz throw contartar and salt, constantly stirring them, till by boil-siderable light not only on the nature of the food ing they become white; after which, taking them of plants, but likewise on the renovation and imout, and drying them, give them another hammer-provement of soils. It is contended by this ingeing, till they are made fit for your purpose. How- nious philosopher, in an able essay, inserted in the ever, care must be taken not to give the foils too thirty-seventh volume of the Annals of Agriculmuch heat, for fear of melting; nor must they be too long boiled, for fear of attracting too much salt. The manner of polishing foils is as follows: take a plate of the best copper, one foot long, and about five or six inches wide, polished to the greatest

ture, that the surest way of finding out the real nourishment of organized bodies, seems to be to inquire what is the substance without which they inevitably perish, and which alone is sufficient to continue their life. All animals require two ingre

dients for the continuation of their existence; viz. atmospheric air, and moist food, derived either from animal or vegetable substances; which food being received into the stomach or some reservoir destined for that purpose, and being gradually digested and changed into different substances in the different organs, is applied to the whole economy of the animal body. Vegetables being deprived of progressive motion, by which means the greatest number of animals go in search of food, must find in the narrow compass or space they occupy every thing necessary for their subsistence. As they are in contact with two substances only, the earth and the atmospheric air, their nourishment must, he thinks, exist in either of them, or in both.

in itself; and that the air thrown out by them in the shade, or in the dark, is in itself, that is to say, being free from other air, the most active poison in destroying animal life yet known.

FOOT. In the Latin and Greek poetry, a metre or measure, composed of a certain number of long and short syllables. These feet are commonly reckoned twenty-eight in number; of which some are simple, as consisting of two or three syllables, and therefore called disyllabic or trisyllabic feet: others are compound, consisting of four syllables, and are therefore called tetrasyllabic feet.

FORCE. In Philosophy, denotes the cause of It is stated, that when he engaged in the experi- the change in the state of a body, when being at iments on vegetables, which he published in 1779 rest, it begins to move, or has a motion which is in English, and in 1780 more fully in French, Dr. either not uniform or not direct. While a body Priestley had already observed that vegetables pos- remains in the same state, either of rest or of unisessed a power of correcting bad air; which how- form and rectilinear motion, the cause of its reever was denied by Mr. Scheele in Sweden, who maining in such a state is in the nature of the body, found that plants, instead of correcting bad air, and it cannot be said that any extrinsic force has corrupted good air. This contradiction struck Dr. acted on it. This internal cause or principle is Priestley so much, that he employed the summer called inertia. Mechanical forces may be reduced of 1778 in repeating his former experiments; and to two sorts; one of a body at rest, the other of a after the most accurate researches he concluded, body in motion. The force of a body at rest, is that though there seems to be such a power in that which we conceive to be in a body lying still, plants, yet that very often they have quite a con- on a table, or hanging by a rope, or supported by a trary effect, as Mr. Scheele found; but that he did spring, &c., and this is called by the names of not know what the reason of this uncertain effect pressure, tension, force, or vis mortua, solicitatio, of plants on air was. In 1778 he found, by acci- conatus movendi, conamen, &c. To this class also dent, that by exposing well-water a long while to of forces we must refer centripetal and centrifugal the sun, it produced a filmly greenish sediment, forces, though they reside in a body in motion; which produced pure air in the sunshine: by ex-beeause these forces are homogeneous to weights, amining this matter with a microscope, he found it pressures, or tensions of any kind. The force of a destitute of organization, and pronounced it to be body in motion is a power residing in that body so neither an animal nor a vegetable substance, but a long as it continues its motion; by means of which substance sui generis, to which he gave the name it is able to remove obstacles lying in its way; to of green matter. M. Berthollet found also, that by lessen, destroy, or overcome the force of any other exposing dephlogisticated marine acid to the sun, moving body, which meets it in an opposite direcvital air was produced; and Mr. Scheele in Swe- tion; or to surmount any dead pressure or resistden found that the same air was also produced from ance, as tension, gravity, friction, &c., for some nitrous acid, exposed to the light of the sun. Dr. time; but which will be lessened or destroyed by Ingenhousz asserts, that he was fortunate enough such resistance as lessens or destroys the motion to discover the true reason why plants did some of the body. This is called vis motrix, moving times correct bad air, and sometimes made it worse, force, and by some late writers vis viva, to distinwhich reason was never so much as even suspected guish it from the vis mortua spoken of before; and by either of the above-mentioned philosophers. by these appellations, however different, the same He discovered, in the summer of 1779, that all thing is understood by all mathematicians, viz. that vegetables are incessantly occupied in decomposing power of displacing, of withstanding opposite the air in contact with them, changing a great por- moving forces, or of overcoming any dead resisttion of it into carbonic acid gas or fixed air, which ance, which resides in a moving body, and which, being specifically heavier than atmospheric air, in whole or in part, continues to accompany it, so tends naturally to fall downwards, and being mis- long as the body moves. cible with moisture, salts, and different sorts of earthy substances, is apt to combine with them. FORCE, COMPARATIVE, OF MEN AND HORSES. He also found that the roots, flowers, and fruits, are There are several curious as well as useful obserincessantly employed in this kind of decomposition, vations in Desagulier's Experimental Philosophy, even in the middle of the sunshine; but that the concerning the comparative forces of men and leaves and green stalks alone cease to perform this horses, and the best way of applying them. A operation during the time the sun, or an unshaded horse draws with the greatest advantage when the clear daylight, shines clear upon them, during line of direction is level with his breast; in such a which time they throw out a considerable quantity situation, he is able to draw two hundred pounds of the finest vital air, and moreover make the air eight hours a day, walking about two miles and a in contact with them purer, or more approaching half, an hour. And if the same horse is made to to the nature of vital air. He has indeed stated draw two hundred and forty pounds he can work facts which prove that vital air, produced by vigor- but six hours a day, and cannot go quite so fast. ous plants in the sunshine, is of the greatest purity On a carriage, indeed, where friction alone is to be

render them more malleable and manageable on the anvil.

FORGE is also used for a large furnace, wherein iron ore, taken out of the mine, is melted down; or it is more properly applied to another kind of furnace, wherein the iron ore, melted down and

overcome, a middling horse will draw one thousand pounds. But the best way to try a horse's force is by making him draw up out of a well, over a single pulley or roller; and in such a case, one horse with another will draw two hundred pounds. Five then are found to be equal in strength to one horse, and can, with as much ease, push round the hori-separated in a former furnace, and then cast into zontal beam of a mill, in a walk only nineteen feet wide; whereas, three men will do it in a walk forty feet wide.

The worst way of applying the force of a horse, is to make him carry or draw up hill; for if the hill be steep, three men will do more than a horse, each man climbing up faster with a burden of one hundred pounds weight, than a horse that is loaded with three hundred pounds, a difference which is owing to the position of the parts of the human body being better adapted to climb than those of a horse. On the other hand, the best way of applying the force of a horse, is in an horizontal direction, wherein a man can exert least force; thus a man, weighing one hundred and forty pounds and drawing a boat along by means of a rope coming over his shoulders, cannot draw above twenty-seven pounds, or exert above one-seventh part of the force of a horse employed to the same purpose. The very best and most effectual posture in a man, is that of rowing; wherein he not only acts with more muscles at once for overcoming the resistence, than in any other position; but as he pulls backwards, the weight of his body assists by way

of lever.

FOREMAST OF A SHIP. A large, round piece of timber, placed in the fore part, or fore-castle, and carrying the fore-sail and fore-top-sail yards. Its length is usually eight ninths of the main-mast; and the fore-top-gallant-mast is half the length of the fore-top-mast.

FOREST. In Geography. The Caledonian and Hercynian forests are famous in history. The first was a celebrated retreat of the ancient Picts and Scots; the latter anciently occupied the greatest part of Europe; particularly Germany, Poland, Hungary, &c. In Cæsar's time it extended from the borders of Alsatia and Switzerland to Transylvania, and was computed sixty days' journey long, and nine broad: some parts or cantons thereof are still remaining. The ancients adored forests, and imagined a great part of their gods to reside therein; temples were frequently built in the thickest forests; the gloom and silence whereof naturally inspire sentiments of devotion, and turn men's thoughts within themselves. For similar reasons the Druids made forests the place of their residence, performed their sacrifices, instructed their youth, and gave laws in them.

FORESTALLING. In Law, buying or bargaining for any corn, cattle, victuals, or merchandise, in the way as they come to fairs, or markets, to be sold, before they get thither, with an intent to sell the same again at a higher price.

FORGE. Properly signifies a little furnace, wherein smiths, and other artificers of iron or steel, &c. heat their metals redhot, in order to soften and

sows and pigs, is heated and fused over again, and beaten afterwards with large hammers, and thus rendered more soft, pure, ductile, and fit for use.

Of these there are two kinds: the first is called the finery, where the pigs are worked into gross iron, and prepared for the second, which is called the chafery, where it is farther wrought into bars fit for use.

FORGERY. In Law, the fraudulent making or altering any record, deed, or writing, &c. to the prejudice of another man's right, particularly the counterfeiting the signature of another with intent to defraud, which, by the law of England, is made a capital felony. In the United States, it is punished by imprisonment.

FORGING. In Smithery, the beating or hammering iron on the anvil, after having first made it redhot in the forge, in order to extend it into various forms, and fashion it into works. There are two ways of forging and hammering iron: one is by the force of the hand, in which there are usually several persons employed, one of them turning the iron, and hammering likewise, and the rest only hammering. The other way is by the force of a water-mill, which raises and works several buge hammers beyond the force of man; under the strokes whereof, the workmen present large lumps or pieces of iron, which are sustained at one end by the anvils, and, at the other, by iron chains fastened to the ceiling of the forge.

This last way of forging is only used in the largest works, as anchors for ships, which usually weigh several thousand pounds. For the lighter works, a single man serves to hold, heat, and turn with one hand, while he hammers with the other.

Every purpose the work is designed for, requires its proper heat; for if it be too cold, it will not feel the weight of the hammer, as the smiths call it, when it will not batter under the hammer; and if it be too hot, it will red-sear, that is, break or crack under the hammer.

The several degrees of heats the smiths give their irons, are, first, a blood-red heat; secondly, a white-flame heat; and, thirdly, a sparkling or welding heat.

FORK. Forks are first mentioned in an inventory of a prince's plate, in 1379. Before this period, the knife only was used for the purpose of cutting up food. The use of the fork spread from Italy to the northern parts of Europe. Thomas Coryate is said to have introduced it into England. The use of the fork was considered so great a luxury, that many monastic orders forbade their members to indulge in it. The Asiatics, even to this day, use no forks, as is also the case with the Turks. The Chinese, instead of forks, make use of two small sticks, which they hold in the same hand between different fingers.

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