LIFELIKE. a. (life and like.) Like a liv ing persou (Pope).

LIFESTRING. s. (life and string.) Nerve; string imagined to convey life (Daniel). LIFETIME. s. (life and time.) Continuauce or duration of life (Addison). LIFEWEARY. a. (life and weary.) Wretched; tired of living (Shakspeare).

To LIFT. v. a. (liffta, Swedish.) 1. To raise from the ground; to heave; to elevate; to hold on high (Dryden). 2. To bear; to support: not in use (Spenser). 3. To rob; to plunder (Dryden). 4. To exalt; to clevate mentally (Pope). 5. To raise in fortune (Ecclus.). 6. To raise in estimation (Hook.) 7. To exalt in dignity (Addison). 8. To elevate; to swell, as with pride (Atterbury).

TO LIFT. v. n. To strive to raise by strength (Locke).

LIFT. s. (from the verb.) 1. The manner of lifting (Bacon). 2. The act of lifting (L'Estrange). 3. Effort; struggle (Hudibr.) 4. A load or surcharge of any thing. 5. (In Scottish.) The sky. 6. Lifts of a sail, are ropes to raise or lower them at plea

sure.

LIFTER. s. (from lift.) One that lifts (Psalms).

To LIG. v. n. (leggen, Dutch.) To lie (Spenser).

LIGAMENTS, (Ligament, i, n. from ligo, to bind.) In anatomy, are elastic and strong membranes connecting the extremities of the moveable bones. They are divided into capsular, which surround join's like a bag, and connecting ligaments. The use of the capsular ligaments is to connect the extremities of the moveable bones, and prevent the efflux of synovia; the external and internal connecting ligaments strengthen the extreInities of the moveable bones.

Table of the Ligaments. Ligaments of the lower jaw.-The condyles of the lower jaw are connected with the articular sinuses of the temporal bone by two ligaments, the capsular and lateral ligament.

Ligaments of the occipital bone, and vertebræ of the neck. The condyles of the occipital bone are united with the articular de pressions of the first vertebræ by the cap sular, broad, anterior, and posterior ligaments, the ligaments of the odontoid process, and ligamentum nucha. Ligaments of the vertebra. The vertebrae are connected together by means of their bodies and oblique processes. The bodies by a soft cartilaginous substance, and the processes by ligaments, viz. the transverse ligament of the first vertebræ; the anterior and posterior common; the interspinous; the intertransverse; the intervertebral ligaments; the capsular ligaments of the oblique processes; and the ligaments of the last vertebræ of the loins with the os sa

crum.

Ligaments of the ribs. The posterior extremity of the ribs is united with the ver

tebra; the anterior with the sternum. The ligaments of the posterior extremity are, the capsular ligaments of the greater and lesser heads; the internal and external ligaments of the neck of the ribs; and a ligament peculiar to the last rib. The ligaments of the anterior extremity are, the capsular ligaments of the cartilages of the true ribs, and the ligaments of the ribs inter se.

Ligaments of the sternum. The ligaments connecting the three portions of the sternum to the ribs are, the membrana propria of the sternum; and the ligaments of the ensiform cartilage.

Ligaments of the pelvis. The ligaments which connect the ossa innominata with the os sacrum are, three ligamenta ileo sacra; two sacroischiatic ligaments; two transverse ligaments of the pelvis: the ligamentum obturans of the foramen ovale, and the ligamentum Poupartii, or inguinale. Sce PELVIS.

Ligaments of the os coccygis. The basis of the os coccygis is connected to the apex of the os sacruin, by the capsular and longitudinal ligaments.

Ligaments of the clavicle. The anterior extremity is connected with the sternum and first rib; and the posterior extremity with the acromion of the scapula, by the interclavicular, the capsular ligament, the ligamentum rhomboideum, and in the posterior extremity, the capsular ligament. Ligaments of the scapula. The proper ligaments which connect the scapula with the posterior extremity of the clavicle are, the conoid and trapezoid ligaments.

Ligaments of the humerus. The head of the humerus is connected with the glenoid cavity of the scapula by the capsular liga

ment.

Ligaments of the articulation of the cubit. The elbow joint is formed by the inferior extremity of the humerus, and superior extremities of the ulna and radius. The ligaments connecting these bones are, the capsular, the brachio-cubital, and the brachioradial ligaments.

Ligaments of the radius. The radius is affixed to the humerus, cubit, and carpus, by peculiar ligaments, namely, the supe rior, inferior, oblique, and interosseous ligaments.

Ligaments of the carpus. The ligaments which connect the eight bones of the wrist together, and with the fore-arm and metacarpus, are, the capsular ligament of the carpus; the first and second transverse ligament; the oblique ligaments, and the capsular ligament proper to the bones of the carpus.

Ligaments of the metacarpus. The bones of the metacarpus are in part connected with the second row of bones of the carpus, and in part together, by the articular and interosseous ligaments.

Ligaments of the fingers. The fingers and phalanges are connected together, and with

the metacarpus ; and the thumb with the carpus, by the lateral ligaments of the fingers, and ligament of the thumb with the os trapeziom of the carpus.

Ligaments which keep the tendons of the muscles of the hand in their proper place. The ligaments which keep tendons of the muscles of the hand in their place, are situated partly on the palm and partly on the back of the hand. In the back of the hand are, the external transverse ligament of the carpus, the vaginal, and the transverse ligaments of the extensor tendons. In the palm of the hand are, the internal transverse ligament of the carpus, the vaginal or crucial ligaments of the flexor tendons of the phalanges, and the accessory ligaments of the fexor tendons.

Ligaments of the articulation of the femur. The head of the os femoris is strongly annexed to the acetabulum of the os innominatum, by two very strong ligaments, the capsular ligament, and the ligamentum teres, or restraining ligament.

Ligaments of the articulation of the knee. The knee joint is formed by the condyles of the os femoris, head of the tibia, and the patella. The ligaments are the capsular, the posterior, the external and the internal lateral ligaments, the crucial and the alar ligaments, the ligaments of the semilunar cartilages, and ligaments of the patella.

Ligaments of the fibula. The fibula is connected with the tibia by means of the capsalar ligament of the superior extremity, the interosseous ligament, and the ligaments of the inferior extremity.

Ligaments of the articulation of the tarsus. The inferior extremity of the tibia and fibula forms the cavity into which the astragalus of the tarsus is received. This articulation is effected by the anterior, middle, and posterior ligament of the fibula, the ligamentam tibiæ deltoides, the capsular ligament, and the ligaments proper to the bones of the

tarsus.

Ligaments of the metatarsus. The bones of the metatarsus are connected in part together, and in part with the tarsus, by means of the capsular ligament, the articular ligaments, the transverse ligaments in the back and sole of the foot, and the interosseous ligaments of the metatarsus.

Ligaments of the toes. The phalanges of the toes are united partly together, and partly with the metatarsus, by the capsular and lateral ligaments.

Ligaments which retain the tendons of the muarles of the foot in their proper place.

These ligaments are found partly in the back and partly in the sole of the foot. They are the vaginal ligament of the tibia, the transverse or crucial ligaments of the tarsus, the ligaments of the tendons of the peronei muscles, the laciniated ligament, the vaginal ligament of the extensor muscle and flexor poilicis, the vaginal ligaments of the flexor tendons, the accessory ligaments of the flexor

tendons, and the transverse ligaments of the extensor tendons.

LIGAMENTUM CILIARE. Behind the uvea of the human eye, there arise out of the choroid membrane, from the ciliary circle, white complicated striæ, covered with a black matter, and running from thence backwards, firmly attached to the very thin membrane of the vitreous humour, where it is inserted into the crystalline lens. The fluctuating extremities of these striæ are spread abroad even to the crystalline lens, upon which they lie, but are not affixed. Taken together they are called ligamentum ciliare.

LIGAMENTUM ovarii. The thick round portion of the broad ligament of the uterus, by which the ovarium is connected with the uterus. The ancients supposed this was hollow, to convey the female semen into the uterus.

LIGAMENTS, Chemical analysis of. The membranous, ligamentous, and tendinous parts of the animal body upon minute analysis appear to consist of the same or of similar materials. They are all insoluble in cold water, but by a gentle heat, and after a certain time, they produce an acidity perceptible both by the smell and taste. They readily pass to the putrid fermentation; but what chiefly characterises them is, that when these white membranous, tendinous, and ligamentous parts are put into boiling water, or are submitted to a boiling heat, they gradually be come soft, lose their texture, and are converted into a viscous, clammy, more or less thick liquid, which, on becoming cool, takes the form of a clear jelly, and is of great use in the arts under the name of glue. See GELATIN.

When exposed to a gentle heat without the intervention of water, they become dry, lose their toughness, are transparent, brittle, and easily break with a snapping between the fingers. By a stronger heat they curl up and are contracted; and on continuing the heat they melt, produce a fetid disagreeable smell, although not so empyreumatic as the more animalized parts: they swell and inflame, although the inflammation is somewhat difficult. The coal which remains is light, and easily incinerated, whilst from their af fording the usual products of animal substances in a small degree, they may be looked upon as but slightly animalized.

Ligaments chiefly differ from tendous and membranes, in resisting with a greater obstinacy the action of boiling water, and in retaining their form and even the strength for some time after boiling. How far they resemble coagulated albumen remains to be ascertained. Perhaps they will be found to form a separate genus.

LIGAMENTAL.
LIGAMENTOUS.

ment (Brown. Wiseman).

a. (from ligament.) Composing a liga

Q. LIGARIUS, a Roman pro-consul of Africa, after Considius. In the civil wars

he followed the interest of Pompey, and was pardoned by Cæsar. Cesar, however, and his adherents, were determined on the ruin of Ligarins; but Cicero, by an eloquent oration, still extant, defeated his accusers, and he was pardoned. He became afterwards one of

Caesar's murderers.

LIGATION, s. (ligatio, Latin.) 1. The act of binding. 2. The state of being hound (Addison).

LIGATURE. s. (ligature, French.) 1. Any thing tied round another; bandage (Spectator). 2. The act of binding (Arbuth.). 3. The state of being bound (Mortimer). LIGATURE, in surgery, any thing tied about a part of the body, more especially a bandage, or fillet of cloth or linen, serving to bind the arm, and facilitate the operation of bleeding.

They are called also chords, bands, or strings, and are of different kinds, some fine, others coarse and strong, and are made either of flax, or hemp, or cloth, or silk, or horsehair, according to the nature of the disorder; for these things are almost constantly required. They are used to replace or extend bones that are broken or dislocated; to tie the patients down in lithotomy, amputations, and operations of that kind; to tie up the veins in phlebotomy; to tie up arteries after amputations, or in large wounds; to secure the splints that are applied to fractures; to tie up the processes of the peritoneum, with the spermatic vessels, in castration; and lastly, in taking off warts, and other excrescences by ligature, and in all other operations of this kind.

LIGATURE is also used for a state of impotency, in respect to venery, pretended to be caused by some charm, or witchcraft.

LIGHT. 8. (leohr, Saxon.) 1. That material medium of sight; that body by which we see (Newton). 2. State of the elements, in which things become visible: opposed to darkness (Gen). 3. Power of perceiving external objects by the eye: opposed to blindness (Milton). 4. Day (Milton). 5. Life (Pope). 6. Artificial illumination (Numbers). 7. Illumination of mind; instruction; knowJedge (Bacon). 8. The part of a picture which is drawn with bright colours, or on which the light is supposed to fall (Dryden). 9. Reach of knowledge; mental view (Bac.). 10. Point of view; situation; direction in which the light falls (Addison). 11. Public notice; public view (Pope). 12. The public (Pope). 13. Explanation (Locke). 14. Any thing that gives light; a pharos; a taper; any luminous body (Glanville).

LIGHT. a. (leolit, Saxon.) 1. Not tending to the centre with great force; not heavy (Addison). 2. Not burdensome; easy to be worn, or carried, or lifted; not onerous (Bacon). 3. Not afflictive; easy to be endured (Hooker). 1. Easy to be performed; not difficult (Dryden). 5. Easy to be acted on by any power (Pryden), 6. Not heavily armed (Kolles. 7. Active; nimble (Spens.). . Enencumbered; unembarrassed; clear of impediments (Bacon). 9. Slight; not great (Boyle). 10. Not dense; not gross (Nuinb.). 11. Easy to admit any influence; unsteady; unsettled; loose (Shakspeure). 12. Gay; airy; wanting dignity or solidity; trifling (Shakspeare). 13. Not chaste; not regular in conduct (Shakspeare). 14. (from light, s.) Bright; clear (Genesis). 15. Not dark; tending to whiteness (Dryden).

Το

woman.

LIGATURE, in mathematics, is a term used by Dr. Wallis, to signify compendious notes or characters by which the sums, differences, rectangles, sums of squares, &c. of quantities are designated; so that results of operations may be very concisely expressed. ↑ Dr. Wallis gives, at pages 67, 111, &c. of his Algebra, several instances of the use of these ligatures, from Oughtred's Clavis.

LIGATURE, in music, is a band, or link, by which notes are connected and tied toge ther. At present we only tie the tails of quavers and notes of shorter duration: but the old masters tied or linked together the heads of their square notes.

LIGER, or LIGERIS, a large river of Gaul, falling into the ocean, now called la Loire.

2.

LIGHT, among philosophers, signifies some. times that principle or substance (whichever it be) by which objects are made perceptible to our sense of seeing,-sometimes the sensation occa. sioned in the mind by the view of luminous objects. In the former of these senses principally we

shall consider it here.

which renders their image present to us-their image, which has so many things to say! The eye, more susceptible than the other senses of multifarious impressions, by the aid of light takes in at once in bodies the forms by which they are limited, the colours that embellish them, their relative positions, and the motions by which they are transported in space. It discriminates, without confusion, all those modifications that seem to sport in a thousand different ways in that grand diversity of objects to which a single look can extend itself.

But if vision were direct only, even that part of the human structure in which the eye has its seat, that which characterises us and makes us known to others, would remain unknown to our selves. Light remedies this disadvantage, by faith. faily exhibiting our portraiture behind reflecting sur. faces, which have the quality of multiplying whatever is presented before them.

Nor are these all the benefits we derive from its properties. Beyond the globes that shine over our beads, there are other luminaries which the eye cannot reach on account of their immense distance, while near us exist a thousand organized beings that equally escape observation from their extreme diminutiveness. Light, by bending itself in transparent bodies terminated by curvili Dear surfaces, has enabled us to perceive these two kinds of infinity, has opened to astronomy a new heaven, and a new field to natural hi

story.

There is this advantage in the theory of light, that the course of this fluid is geometrical ; so that by a few simple laws, and a precise and rigorous system, results may be obtained without much difficulty. It is well known that the cele brated Saunderson, though blind almost from his birth, delivered public lectures on optics: he considered the rays of light as simple material lines, that acted on the eye by contact; and seeing these lines in bis imagination, he succeeded in making others comprehend how their eyes perceived the very objects of which the lines excited in them the impression.

The nature of light has been a subject of speculation from the first dawnings of philosophy. Some of the earliest philosophers doubted whether objects became visible by means of any thing pro. ceeding from them, or from the eye of the spectatot. But this opinion was qualified by Empe docles and Plato, who maintained, that Vision was occasioned by particles continually flying off from the surfaces of bodies, which meet with others proceeding from the eye; while the effect was ascribed by Pythagoras solely to the particles proceeding from the external objects, and entering the pupil of the eye. But Aristotle defines light to be the act of a transparent body, considered as such: and he observes that light is not fire, nor yet any matter radiating from the luminous body, and transmitted through the transparent

one.

The Cartesians have refined considerably on this notion; and hold that light, as it exists in the luminous body, is only a power or faculty of exciting in us a very clear and vivid sensation; or that it is an invisible fluid present at all times and in all places, but requiring to be set in motion, by a body ignited or otherwise properly qualified to make objects visible to us.

Father Malebranche explains the nature of light from a supposed analogy between it and sound. Thas he supposes all the parts of a luminous body

are in a rapid motion, which, by very quick pulses, is constantly compressing the subtle matter between the luminous body and the eye, and excites vibrations of pression. As these vibrations are greater, the body appears more luminous; and as they are quicker or slower, the body is of this or that colour.

But the Newtonians maintain, that light is not a fluid per se, but consists of a great number of very small particles thrown off from the luminous body by a repulsive power with an immense veloeity, and in all directions. These particles, it is also held, are emitted in right lines: which rectilinear motion they preserve till they are turned out of their path by some of the following causes, viz. by the atraction of some other body near which they pass, which is called inflection; or by passing obliquely through a medium of different density, which is called refraction; or by being turned aside by the opposition of some intervening body, which is called reflection; or lastly, by being totally stopped by some substance into which they penetrate, and which is called their extinction. A succession of these particles following one another, in an exact straight line, is called a ray of light; and this ray, in whatever manner its direction may be changed, whether by refraction, reflection, or inflection, always preserves a rectilinear course till it be again changed; neither is it possible to make it move in the arch of a circle, ellipsis, or other curve. For the above properties of the rays of light, see the several words, REFRACTION, REFLECTION, &C.

The velocity of the particles and rays of light is truly astonishing, amounting to near two hundred thousand miles in a second of time, which is near a million times greater than the velocity of a cannon-ball. This amazing motion of light has been manifested in various ways, and first, from the eclipses of Jupiter's satellites. It was first observed by Roemer, that the eclipses of those satellites happen sometimes sooner, and sometimes later, than the times given by the tables of them; and that the observation was before or after the

computed times, according as the earth was nearer to, or farther from Jupiter, than the mean distance. Hence Roemer and Cassini both concluded that this circumstance depended on the distance of Jupiter from the earth; and that, to account for it, they must suppose that the light was about 14 minutes crossing the earth's orbit. This conclusion however was afterward abandoned and attacked by Cassini himself. But Roemer's opinion found an able advocate in Dr. Halley; who removed Cassini's difficulty, and left Roemer's conclusion in its full force. Yet, in a memoir presented to the academy in 1707, M. Maraldi endeavoured to strengthen Cassini's arguments; when Roemer's doctrine found a new defender in Mr. Pound. See Philos. Traus. number 136. It has since been found, by repeated experiments, that when the earth is exactly between Jupiter and the sun, his satellites are seen eclipsed about eight minutes and a quarter sooner than they could be according to the tables; but when the earth is nearly in the opposite point of its orbit, these eclipses happen about eight minutes and a quarter later than the tables predict them. Hence then it is certain that the motion of light is not instantaneous, but that it takes up about 16 minutes and a half of time to pass over a space equal to the diameter of the earth's orbit, which is at least 190 millions of miles in length, or at the rate of near 200,000 miles per second, as above men

tioned. Hence, therefore, light takes up about eight minutes and a quarter in passing from the sun to the earth; so that, if he should be annihilated, we would see him for eight minutes and a quarter after that event should happen; and if he were again created, we should not see him till eight minutes and a quarter afterwards. Hence also it is easy to know the time in which light travels to the earth from the moon, or any of the other planets, or even from the fixed stars when their distances shall be known; these distances however are so immensely great, that from the nearest of them, supposed to be Sirius, the dog-star, light takes up many years to travel to the earth; and it is even suspected that there are many stars whose light have not yet arrived at us since their creation. And this, by-the-bye, may perhaps sometimes account for the appearance of new stars in the heavens.

It may be just observed, that Galileo first conceived the notion of measuring the velocity of light; and a description of his contrivance for this purpose, is in his Treatise on Mechanics, page 39. He had two men with lights covered; the one who was to observe when the other uncovered his light, and to exhibit his own the moment he perceived it. This rude experiment was tried at the distance of a mile, but without success, as may naturally be imagined: the members of the Academy Del Cimento repeated the experiment, and placed their observers, to as little purpose, at the distance of two miles.

But our exellent astronomer Dr. Bradley, afterwards found nearly the same velocity of light as Roemer, from his accurate observations, and most ingenious theory, to account for some apparent motions in the fixed stars; for an account of which, see ABERRATION of Light. By a long series of these observations, he found the difference between the true and apparent place of several fixed stars, for different times of the year; which difference could no otherwise be accounted for, than from the progressive motion of the rays of light. From the mean quantity of this difference he ingeniously found, that the ratio of the velocity of light to the velocity of the earth in its orbit, was as 10313 to 1, or that light moves 10313 times faster than the earth moves in its orbit about the sun; and as this latter motion is at the rate of 121 miles per second nearly, it follows that the former, or the velocity of light, is at the rate of about 195000 miles in a second: a motion according to which it will require just 8′ 7′′ to move from the sun to the earth, or about 95 millions of miles.

It was also inferred, from the foregoing principles, that light proceeds with the same velocity from all the stars. Whence it follows, if we suppose that all the stars are not equally distant from us, as many arguments prove, that the motion of light, all the way it passes through the immense space above our atmosphere, is equable or uniform. Since the different methods of determining the velocity of light thus agree in the result, it is reasonable to conclude that, in the same medium, light is propagated with the same velocity after it has been reflected as before.

To the doctrine concerning the materiality of light, and its amazing velocity, several objections have been made; of which the most considerable is, that as rays of light are continually passing in different directions from every visible point, they must necessarily interfere with each

such a manner, as entirely to confound

all distinct perception of objects, if not quite to destroy the whole sense of seeing; not to mention the continual waste of substance which a constant emission of particles must occasion in the luminous body, and thereby since the creation must have greatly diminished the matter in the sun and stars, as well as increased the bulk of the earth and planets by the vast quantity of particles of light absorbed by them in so long a period of

time.

But it has been replied, that if light were not a body, but consisted in mere pression or pulsion, it could never be propagated in right lines, but would be continually inflected ad umbram. Thus Sir I. Newton: "A pressure on a fluid medium, i. e. a motion propagated by such a medium, beyond any obstacle which impedes any part of its motion, cannot be propagated in right lines, but will be always inflecting and diffusing itself every way, to the quiescent medium beyond that obstacle. The power of gravity tends downwards; but the pressure of water arising from it tends every way with an equable force, and is propagated with equal ease and equal strength, in curves, as in straight lines. Waves, on the surface of the water, gliding by the extremes of any very large obstacle, inflect and dilate themselves, still diffusing gradually into the quiescent water beyond that obstacle. The waves, pulses, or vibrations of the air, wherein sound consists, are manifestly inflected, though not so considerably as the waves of water; and sounds are propagated with equal case, through crooked tubes, and through straight lines; but light was never known to move in any curve, nor to inflect itself ad umbram."

It must be acknowledged, however, that many philosophers, both English and foreigners, have recurred to the opinion, that light consists of vibrations propagated from the luminous body, through a subtle ethereal medium.

The ingenious Dr. Franklin, in a letter dated April 23, 1752, expresses his dissatisfaction with the doctrine, that light consists of particles of matter continually driven off from the sun's surface, with so enormous a swiftness. Must not," says he, "the smallest portion conceivable, have, with such a motion, a force exceeding that of a 24 pounder discharged from a cannon? Must not the sun diminish exceedingly by such a waste of matter; and the planets, instead of drawing nearer to him, as some have feared, recede to greater distances through the lessened attraction? Yet these particles, with this amazing motion, will not drive before them, or remove, the least and slightest dust they meet with; and the sun appears to continue of his ancient dimensions, and his attendants move in their ancient orbits." He therefore conjectures that all the phenomena of light may be more properly solved, by suppos ing all space filled with a subtle elastic fluid, which is not visible when at rest, but which, by its vibrations, affects that fine sense in the eye, as those of the air affect the grosser organs of the ear; and even that different degrees of the vibration of this medium may cause the appearances of different colours. Franklin's Exper. and Observ. 1769, page 264. To this hypothesis of vibrations there is a very strong objection, to which, though it has often been attempted, no satisfactory an. swer has been given; for, according to this hypothesis, light would not only spread itself in a direet line, but its motion would be transmitted in every direction like that of sound, and would con