The amnion is firm, thin, transparent, and possessing no visible vessels. It immediately includes the liquor amnii and child. The chorion lies outside of the amnion, and adheres to it; it is transparent, very thin and tender, and adheres externally to the decidua.

The decidua is an efflorescence of the internal coat of the uterus, produced after conception, in order to adapt the womb for the ovum, which is to enter it. It is shed after every birth, or miscarriage, with the other membranes; and hence its name. It is thicker, but more delicate and tender than the amnion or chorion. It contains several blood vessels, which are best seen in recently discharged secundines. It adheres closely to the uterus on one side, and to the chorion on the other. The laceration of the vessels, which this membrane receives from the uterus, accounts for the hemorrhage which follows its separation. At the edge of the placenta it divides into two layers, which pass over the two surfaces of that organ, and form its uterine portion.

The liquor amnii is the fluid immediately surrounding the body of the child, and so called from the membrane enclɔsing it. Its usual quantity is about two pints. It is a clear, transparent fluid.

The child, while in the uterus, is naturally contracted into an oval form, adapted to the figure and circumstances of its habitation. The vertex of the head makes one end of the oval, and the nates the other. One side or edge of the oval is formed by the occiput, the back part of the neck, and the incurvated trunk; the other is made by the forehead and the mass of contracted and conglomerated limbs. The chin is close to the breast, the trunk bended forwards, the knees close to the fore parts of the hy pochoridia, the legs drawn to the back parts of the thighs, and the upper extremities contracted into the vacant space betwixt the forehead and knees. The more or less compact form of the child depends on the quantity of liquor amnii; when that is small, the uterus moulds the child into various forms, and often produces deformities of the limbs. The head is placed downwards with respect to the mother, and the nates upwards.

The usual weight of the child at the time of birth is from five to eight pounds: of several thousands weighed at the British Lying-in Hospital, the largest weighed 11lb. 2oz. the smallest was above 4lb.

The head, upper part of the trunk, and

upper extremities, are very large when compared with the lower parts of the body. The surface of the skin is covered pretty generally with a crust of a white sebaceous

matter.

Peculiarities in the Structure of the Fœtus.

These are on the whole numerous; but we shall briefly enumerate the most important only.

The first which claim our attention are some points respecting the heart and large blood-vessels; which we may suppose absolutely necessary to the life of the child, while it draws nourishment from the mother, and cannot enjoy respiration. As the fœtus in utero cannot breathe, the circulation of its blood through the lungs would be useless: hence that fluid can go from the right to the left side of the heart by means of an opening called the foramen ovale, and placed between the two auricles, and of a communicating canal from the pulmonary artery to the aorta, called ductus arteriosus. The umbilical arteries are continuations of the internal iliacs, taking the blood from the child to the placenta; from which it is brought back by the umbilical vein, and circulated through the liver.

The lungs are small and compact; and as they have not yet received air, they are specifically heavier than water. This is an important point, and is usually referred to in trials for child-murder, in order to determine whether the child was born alive or no. If the lungs sink in water, it is considered a still-born case; and if they float, the probable inference is, that the child has breathed, but it would be a very rash conclusion that it had, therefore, been murdered.

Much caution and consideration of concomitant circumstances must be employed in making use of this proof. Putrefaction will disengage air that may make the lungs float.

The thymus gland, in the chest, is very large in the foetus; it gradually shrinks after birth, until it entirely disappears. Its use is unknown.

The pupil of the eye is shut until the seventh or eighth month, by a thin pellicle called membrana pupillaris. As a general observation, the eye and ear are very per fect at the time of birth, and almost as large as they ever will be. (N.B. This does not apply to the external ear.)

The small intestines have no valvule conniventes. The large are filled with a

dark green mucous, and semifluid substance, called meconium. The liver is of an immense size, and fills two-thirds of the belly.

The renal capsules are very large, equal indeed to the kidnies themselves. Their use is unknown..

The testicle is placed originally in the abdomen, near the kidney; but it passes into the scrotum towards the latter periods of gestation. Sometimes it does not descend on one or both sides till after birth, and sometimes not even during life.

Of the Uterus and its Contents in the earlier

Months of Pregnancy.

The conception at first is lodged entirely in the fundus uteri; and no part of it extends into the cervix; which, on the contrary, remains contracted and hard, and filled with a tough and firm jelly. The neck, however, is gradually distended, so that at last there is no distinction between it and the fundus.

The corpus luteum is larger and more vascular, and contains a cavity filled with fluid.

There is a small membranous bag placed on the outer surface of the amnion, and connected to the navel-string, called the vesicula umbilicalis.

The chorion is at first covered all over with fine shaggy and floating processes, which are continuations of the umbilical vessels. By these it adheres to the decidua, and derives its nourishment and supply. These processes are the fœtal portion of the placenta at that time. As the ovum increases they disappear from the general surface of the chorion; become confined to one part, and form the fleshy mass of the placenta.

The decidua is most manifest in the early state of conception, and is thickest at that time. It adheres to the uterus by numerous fine flocculent processes. It is formed by the uterus previously to the entrance of the ovum into its cavity; and is even formed in cases of extra uterine fœtus, where the ovum never enters the uterus.

The placenta does not exist in a very young ovum. The whole outer surface of the chorion is covered with shaggy vessels. In the course of a few weeks one half of the membrane becomes smooth, the remainder being covered as before. These vessels, at their floating extremities, are covered with decidua; and these parts, which at first are separable, gradually become intimately

connected, and form a firm mass adhering to the uterus, which is the placenta.

The navel-string is not visible till towards the sixth or seventh week.

The foetus is discernable about the fourth week after conception. In a particular instance, a very small fœtus. was discernible where, from peculiar circumstances, the conception was clearly ascertained to be twenty-two days old.

At this period it consists of two oval masses, the head and trunk; of which the former is bent forwards upon the chest; the eyes are very conspicuous, and form large black prominences; the mouth and tongue are discernible; the body forms a larger and longer oval than the head, with the lower part of the spine curved towards the belly: the upper extremities sprout out from each side of the chest; and the lower from the lower part of the trunk, being considerably smaller than the upper.

FOG, or MIST, a meteor consisting of gross vapours, floating near the surface of the earth. See METEOROLOGY.

FOIL, among glass-grinders, a sheet of tin, with quicksilver or the like, laid on the backside of a looking-glass, to make it reflect.

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 colour, either deep or pale. Thus, if you want a stone to be of a pale colour, put a foil of that colour under it; or if you would have it deep, lay a dark one under it.

FOLIATE, in the higher geometry, a name given by M. de Moivre to a curve of the second order, expressed by the equation x3+y3=axy; being a species of defective hyperbolas with one asymptote, and consisting of two infinite legs crossing one another, and forming a sort of leaf.

FOLIATING of looking-glasses, the 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 loaden

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. Foliating of globe looking-glasses is done as follows: take five ounces of quicksilver, and one ounce of bismuth; of lead and tin half an ounce each. First put the lead and tin into fusion, then put in the bismuth, and when you perceive that in fusion too, let it stand till it is almost cold, and pour the quicksilver into it: after this, take the glass globe, which must be very clean, and the inside free from dust; make a paper funnel, which put into the hole of the globe, as near to the glass as you can, so that the amalgam, when you pour it in, may not splash, and cause the glass to be full of spots; pour it in gently, and move it about, so that the amalgam may touch every where. If you find the amalgam begin to be curdly and fixed, then hold it over a gentle fire, and it will easily flow again. And if you find the amalgam too thin, add a little more lead, tin, and bismuth to it. The finer and clearer your globe is, the better will the lookingglass be.

FOLIO, in merchants' books, denotes a page, or rather both the right and left hand pages, these being expressed by the same figure, and corresponding to each other.

FOLIO, among printers and booksellers, the largest form of books, when each sheet is so printed, that it may be bound up in two leaves only. This form is only used in large works; but the quarto or octavo forms are much more handy.

FOLKMOTE, or FOLCMOTE, according to Kennet, was the common-council of all the inhabitants of a city, town, or borough: though Spelman will have the folkmote to have been a sort of annual parliament or convention of the bishops, thanes, aldermen, and freemen on every May-day. Dr. Brady, on the contrary, tells us, that it was an inferior court, held before the King's reeve, or his steward, every month, to do folk right.

FOMAHAUT, in astronomy, a star of the first magnitude in the constellation Aquarius,

FOMENTATION, in medicine, the bathing any part of the body with a convenient liquor; which is usually a decoction of herbs, water, wine, or milk; and the applying of bags stuffed with herbs and other ingredients, which is commonly called

dry fomentation. Fomentations differ in little else from embrocations, but that they are mostly made with aqueous menstrunms, are more extensive in their manner of application, and are assisted by actual heat, and hot woollen cloths: add to this, that fomentations, when general, or applied to every part of the body, are called baths.

FONT, among écclesiastical writers, a large bason, in which water is kept for the baptizing of infants, or other persons. It is so called, probably, because baptism was usually performed among the primitive christians at springs or fountains. In process of time the font came to be used, being placed at the lower end of the church, to intimate, perhaps, that baptism is the rite of admis sion into the Christian church.

FONT. See FOUNT.

FONTANESIA, in botany, so named in honour of Mons. Desfontaines, a genus of the Diandria Monogynia class and order, Natural order of Sepiariæ. Jasmineæ, Jussieu. Essential character: calyx fourparted, inferior; petals two, two-parted; capsule membranaceous, not opening, twocelled; cells one-seeded. There is but one species,

FONTINALIS, in botany, a genus of the Cryptogamia Musci, or Mosses. Generic character: capsule oblong, with the mouth ciliate; opening with an acuminate lid; covered with a sessile, smooth, conical veil; included in a pitcher-shaped, imbricate perichætium. Only four species are known, and they are all natives of England: three of them are water mosses, and one grows upon trees. Professor Martyn says, that several new species have been discovered by Swartz in the West Indies,

FOOD, implies whatever aliments are taken into the body to nourish it. See DIETETICS.

FOOL, according to Mr. Locke, is a person who makes false conclusions from right principles; whereas a madman, on the contrary, draws right conclusions from wrong principles.

FOOT, pes, a part of the body of most animals, whereon they stand, walk, &c.

Animals are distinguished, with respect to the number of their feet, into bipedes, two-footed; such are men and birds: quadrupedes, four-footed; such are most landanimals: and multipedes, or many-footed; as insects. The reptile-kind, as serpents, &c. have no feet; the crab-kind of fish have got ten feet, but most other fishes have no feet at all; the spider, mites, and polypuses

have eight; flies, grass-hoppers, and butterflies have six feet; animals destined to swim, and water-fowl, have their toes webbed together, as the phoce, goose, duck, &c.; the fore-feet of the mole, rabbit, &c. are wonderfully formed for digging and scratching up the earth, in order to make way for their head.

FOOT. See ANATOMY.

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, 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.

Foor is also a long measure, consisting of twelve inches. Geometricians divide the foot into ten digits, and the digit into ten lines. See DIGIT and Line.

Foot square, is the same measure both in breadth and length, containing 144 square or superficial inches.

FOOT cubic, or solid, is the same measure in all the three dimensions, length, breadth, and depth or thickness, containing 1728 cubic inches. The foot is of different lengths in different countries. The Paris royal foot exceeds the English by nine lines; the ancient Roman foot of the Capitol consisted of four palms, equal to 11 inches English; Rhineland or Leyden foot, by which the northern nations go, is to the Roman foot, as 950 to 1000. See MEASURE.

Foor gell, or Faut-geld, in our old enstoms, an amercement laid upon those who live within the bounds of a forest, for not lawing or cutting out the ball of their dog's feet. To be free of a foot-geld, was a privilege to keep dogs unlawed, within the bounds of a forest.

FOOT level, among artificers, an instrument that serves as a foot-ruie, a square, and a level. See LEVEL.

FORAGE, in military affairs, implies hay, straw, and oats, for the subsistence of the army horses. It is divided into rations, of which one is a day's allowance for a horse, and contains 20lb. of hay, 10lb. of oats, and 5lb. of straw. When cavalry is stationed in barracks in Great Britain, the number of rations of forage is, to field-officers four, supposing them to have four effective horses; to captains three; to staff. officers two; to quarter-masters, non-commissioned officers, and privates, each one.

On foreign service, this article is governed by circumstances.

FORAMEN, in anatomy, a name given to several apertures, or perforations in divers parts of the body; as, the foramen lachrymale, &c. See ANATOMY.

FORCE, in mechanics, denotes the cause of the change in the state of a body when being at rest it begins to move, or has a motion which is either not uniform, or not direct. Mechanical forces may be reduced to two sorts, one of a body at rest, the other of a body in motion. See MECHANICS. The force of a body at rest is that which we conceive to be in a body lying still on a table, or hanging by a rope, or supported by a spring, and is called by the names of pressure, vis mortua, &c. The which the table is pressed, or the spring measure of this force being the weight with

bent.

The force of a body in motion, called moving force, vis motrix, and vis viva, to distinguish it from the vis mortua, is allowed to be a power residing in that body so long as it continues its motion, by means of which it is able to remove obstacles lying in its way, to surmount any resistance, as tension, gravity, friction, &c. and which, in whole or in part, continues to accompany it so long as the body moves.

We have several curious, as well as useful observations, in Desagulier's “Experimental Philosophy," concerning the comparative forces of men and horses, and the best way of applying them. A horse draws with the greatest advantage when the line of direction is level with his breast; in such a situation, he is able to draw 200lb. eight hours a-day, walking about two miles and a half an hour. And if the same horse is made to draw 240lb. he can work but six hours a-day, and cannot go quite so fast. On a carriage indeed, where friction alone is to be overcome, a middling horse will draw 1000lb. 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 200lb., as already observed. Five men are found to be equal in strength to one horse, and can, with as much ease, push round the horizontal beam of a mill, in a walk forty feet wide; whereas three men will do it in a walk only nineteen 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

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. Foliating of globe looking-glasses is done as follows: take five ounces of quicksilver, and one ounce of bismuth; of lead and tin half an ounce each. First put the lead and tin into fusion, then put in the bismuth, and when you perceive that in fusion too, let it stand till it is almost cold, and pour the quick silver into it: after this, take the glass globe, which must be very clean, and the inside free from dust; make a paper funnel, which put into the hole of the globe, as near to the glass as you can, so that the amalgam, when you pour it in, may not splash, and cause the glass to be full of spots; pour it in gently, and move it about, so that the amalgam may touch every where. If you find the amalgam begin to be curdly and fixed, then hold it over a gentle fire, and it will easily flow again. And if you find the amalgam too thin, add a little more lead, tin, and bismuth to it. The finer and clearer your globe is, the better will the looking glass.be.

FOLIO, in merchants' books, denotes a page, or rather both the right and left hand pages, these being expressed by the same figure, and corresponding to each other.

FOLIO, among printers and booksellers, the largest form of books, when each sheet is so printed, that it may be bound up in two leaves only. This form is only used in large works; but the quarto or octavo forms are much more handy.

FOLKMOTE, or FOLCMOTE, according to Kennet, was the common-council of all the inhabitants of a city, town, or borough: though Spelman will have the folkmote to have been a sort of annual parliament or convention of the bishops, thanes, aldermen, and freemen on every May-day. Dr. Brady, on the contrary, tells us, that it was an inferior court, held before the King's reeve, or his steward, every month, to do folk right.

FOMAHAUT, in astronomy, a star of the first magnitude in the constellation Aquarius.

FOMENTATION, in medicine, the bathing any part of the body with a convenient liquor; which is usually a decoction of herbs, water, wine, or milk; and the applying of bags stuffed with herbs and other ingredients, which is commonly called

dry fomentation. Fomentations differ in little else from embrocations, but that they are mostly made with aqueous menstruams, are more extensive in their manner of application, and are assisted by actual heat/ and hot woollen cloths: add to this, that fomentations, when general, or applied to every part of the body, are called baths.

FONT, among écclesiastical writers, a large bason, in which water is kept for the baptizing of infants, or other persons. It is so called, probably, because baptism was usually performed among the primitive christians at springs or fountains. In process of time the font came to be used, being placed at the lower end of the church, to intimate, perhaps, that baptism is the rite of admis sion into the Christian church.

FONT. See FOUNT.

FONTANESIA, in botany, so named in honour of Mons. Desfontaines, a genus of the Diandria Monogynia class and order. Natural order of Sepiariæ. Jasmineæ, Jussieu. Essential character: calyx fourparted, inferior; petals two, two-parted; capsule membranaceous, not opening, two. celled; cells one-seeded. There is but one species,

FONTINALIS, in botany, a genus of the Cryptogamia Musci, or Mosses. Generic character: capsule oblong, with the mouth ciliate; opening with an acuminate lid; covered with a sessile, smooth, concal veil; included in a pitcher-shaped, imbricate perichætium. Only four species are known, and they are all natives of England: three of them are water mosses, and one grows upon trees. Professor Martyn says, that several new species have been discovered by Swartz in the West Indies.

FOOD, implies whatever aliments are taken into the body to nourish it. See DIETETICS.

FOOL, according to Mr. Locke, is a person who makes false conclusions from right principles; whereas a madman, on the contrary, draws right conclusions from wrong principles,

FOOT, pes, a part of the body of most animals, whereon they stand, walk, &c.

Animals are distinguished, with respec to the number of their feet, into bipedes two-footed; such are men and birds: que drupedes, four-footed; such are most land animals: and multipedes, or many-footed as insects. The reptile-kind, &c. have no feet; the crab-k got ten feet, but most of feet at all; the spider.