the upper part of the belly: size, that of a squirrel. Inhabits Ceylon; agile, quick of hearing, monogamous, 3. L. Mongor. Mongor, or woolly maucauco. Size of a cat, eyes lodged in a circle of black, and the space between them of the same colour; iris of an orange colour; short round ears; the end of the nose black; the rest of the nose, and the lower sides of its cheeks, white. When in full health, the whole upper part of the body covered with long soft and thick fur, a little curled or waved, of a deep brownish ash-colour; tail very long, and covered with the same sort of hair of the same colour; breast and belly white; hands and feet naked and dusky; nails, as in the two former species, flat; except that of the inner toe of the hind feet; it varies sometimes, with white or yellow paws, and a face wholly brown. It inhabits Madagascar and the adjacent isles; turns its tail over its head to protect it from rain; feeds on fruits, and sleeps on trees; it is very good natured, and very sportive; but very tender: it is found as far as Celebes or Macassar. Buffon gives the history of one that he had in his possession for several years. He says, that its tongue was rough like that of a cat; that when permitted, it would continue to lick a person's hand till it was inflamed, and often finished this operation with a severe bite. It amused itself with gnawing its own tail, and actually destroyed four or five vertebræ. Whenever it could escape, it went into the neighbouring shops in quest of fruits, sugar, and sweet meats, opened the boxes that contained them, and helped himself. Dreaded cold and moisture; in cold weather never left the fire, and would stand on end to warm itself. Its movements were extremely brisk, and sometimes petulant; often slept during the day; but awoke with the slightest noise. 4. L. Macao. Vari. Tailed; black; collar bearded. Three other varieties: 6 body brown; y body white; black and white mixed. Very fierce in a wild state and makes so violent a noise in the woods, that it is easy to mistake the noise of two for that of an hundred; some have compared this noise to the roaring of a little lion. When taken young, and tamed, these animals are very gentle and good natured; their hind legs and thighs, like those of the two preceding species, are very long, which makes their pace sideling and bounding. It inha bits Madagascar. 5. L. Prebensilis. Little maucauco. Tail prehensile size less than that of the black rat; a dark space round the eyes which are very large and full; the upper part of its body ash-coloured, the lower white; head round, nose sharp, and whiskers long; has two canine teeth in each jaw; four cutting teeth in the upper; six in the lower, and seven grinders on each side; ears large, undish, naked, and membranaceous; toes Near 6. L. Volans. Flying maucauco. three feet long, and as broad; very distinct from yet resembling the bat and flying squirrel; inhabits the country about Guzarat, the Molucca isles, and the Philippines; feeds on the fruits of trees, and is called by the Indians, Caguang, Colugo, and Gigna; head long; mouth and teeth small; ears also small, round, and membranous; from the neck to the hands, and thence to the hind feet, extends a broad skin like that of a flying squirrel; the same is continued from the hind feet to the tip of the tail, which is included in it; the body and outside of the skin covered with soft hair, hoary or black, and ash-colour; the inner side of the extended skin appears membranous, with little veins and fibres dispersed throngh it; the legs clothed with a soft yellow down; has five claws on each foot; the claws slender, very sharp, and crooked; with these it strongly adheres to whatever it fastens on; tail slender, and about a span long. From our ignorance of the form of its teeth, its genus is very doubtful; but it is placed here on the authority of Linnéus. LEMURES, the manes of the dead. The ancients supposed that the souls, after death, wandered over the world, and disturbed the peace of its inhabitants. The good spirits were called lares familiares; and the evil ones were known by the name of Larva, or Lemures. They terrified the good, and continually haunted the impious. The Romans celebrated festivals in their honour called Lemuria or Lemuralia, in the month of May. They were first instituted by Romulas to appease the manes of his brother Remus, from whom they were called Remuria, and by corruption Lemuria. LEMURIA and LEMURALIA. See LL MURES. LENA, a large river of Siberia, which flows in a northerly direction, receives 16 other rivers, and falls into the Frozen Ocean, by several mouths. LENÆA, a festival kept by the Greeks in honour of Bacchus, (called Lenæus, from Amos, a wine-press) at which there was much feasting and Bacchanalian jollity, accom panied with poetical contentions, and the exhibition of tragedies. The poor goat was generally sacrificed on the occasion, and treated with various marks of cruelty and contempt, as being naturally fond of browsing on the vine-shoots. To LEND. v. a. preterit and part, pass. lent. (lanan, Saxon.) 1. To afford or supply, on condition of repayment (Dryden). 2. To suffer to be used, on condition that it be restored (Shakspeare). 3. To afford; to grant in general (Addison). LE'NDER. 8. (from lend.) 1. One who lends any thing. 2. One who makes a trade of putting money to interest (Addison). LENFANT (JAMES), a learned French writer, born in 1661. After studying at Saumur, he went to Heidelberg, where he received imposition of hands for the ministry in 1684. He discharged the functions of this character with great reputation there, as chaplain of the electress dowager Palatine, and pastor in ordinary to the French church. The descent of the French into the Palatinate obliged our author to depart from Heidelberg in 1688. He went to Berlin, where the elector Frederic, afterwards king of Prussia, appointed him one of the ministers. There he continued 39 years, distinguishing himself by his writings. He was preacher to the queen of Prussia, Charlotta Sophia; and after her death, to the late king of Prussia. In 1707 he took a journey to England and Holland, where he had the honour to preach before Queen Anne; and might have settled in London, with the title of chaplain to her majesty. In 1712 he went to Helmstadt, in 1715 to Leipsic, and in 1725 to Breslaw, to search for rare books and MSS. It is not certain whether it was he that first formed the design of the Bibliotheque Germanique, which began in 1720; or whether it was suggested to him by one of the society of learned men, which took the name of Anonymous, and who ordinarily met at his house. He died in 1728. His principal works are, 1. The History of the Council of Constance, 2 vols. 4to. 2. A History of the Council of Pisa, 2 vols. 4to. 3. The New Testament, translated from the Greek into the French, with notes by Beausobre and Lenfant, 2 vols. 4to. 4. The History of Pope Joan, from Spanheim's Latin dissertation. 5. Several pieces in the Bibliotheque Choisie, La Republique des Lettres, La Bibliotheque Gerinanique, &c. LENGTH. 8. (from leng, Saxon.) 1. The extent of any thing material from end to end; the longest line that can be drawn through a body (Bacon). 2. Horizontal extension (Dryden). 3. Á certain portion of space or time (Locke). 4. Extent of duration or space (Locke). 5. Long duration or protraction (Addison). 6. Reach or expansion of any thing (Watts). 7. Full extent; uncontracted state (Addison). 8. Distance (Clarendon). 9. End; latter part of any assignable time (Hooker). 10. At LENGTH. At last; in conclusion (Dryden). To LENGTHEN. v. a. (from length.) 1. To draw out; to make longer; to elongate (Arbuthnot). 2. To protract; to continue (Daniel). 3. To protract pronunciation (Dryden). 4. To LENGTHEN out. To protract; to extend (Dryden). To LENGTHEN. v. n. To grow longer; to increase in length (Prior). LENGTHWISE. ad. (length and wise.) According to the length. LE'NIENT. a. (leniens, Latin.) 1. Assuasive; softening; mitigating (Pope). 2. Laxative; emollient (Arbuthnot). LE NIENT. 8. An emollient, or assuasive application (Wiseman). To LE NIFY. v. a. (lenifier, old French.) To assuage; to mitigate (Dryden). LENITIVE. a. (lenitif, Fr. lenio, Lat.) Assuasive; emollient (Arbuthnot). LENITIVE. 8. 1. Any thing medicinally applied to ease pain. 2. A palliative (South). LENITY. 8. (lenitas, Lat.) Mildness mercy; tenderness; softness of temper (Daniel). LENOX, or DUMBARTONSHIRE, a county of Scotland. See DUMBARTONSHIRE. LENS, a piece of glass, or any other transparent substance, the surfaces of which are so formed, that the rays of light, by passing through it, are made to change their direction, either tending to meet in a point beyond the lens, or made to become parallel after converging or diverging; or, lastly, proceeding as if they had issued from a point before they fell upon the lens. Some lenses are convex, or thicker in the middle; some concave, or thinner in the middle; some planoconvex, or plano-concave; that is, with one side flat, and the other convex or concave; and some are called meniscuses, or convex on one side, and concave on the other. See DIOPTRICS. ; LENSES, BLOWN, are used only in the single microscope, and the usual method of making them has been to draw out a fine thread of the soft white glass, called crystal, and to convert the extremity of this into a spherule, by melting it at the flame of a candle. But this glass contains lead, which is disposed to become opake by partial reduction, unless the management be very carefully attended to. We are informed, however, by Mr. Nicholson, that the hard glass used for windows seldom fails to afford excellent spherules. This glass is of a clear bright green colour when seen edgewise. A thin piece was cut from the edge of a pane of glass less than one-tenth of an inch broad. This was held perpendicularly by the upper end, and the flame of a candle was directed upon it by the blow-pipe, at the distance of about an inch from the lower end. The glass became soft, and the lower piece descended by its own weight to the distance of about two feet, where it remained suspended by a thin thread of glass about one five-hundredth of an inch in diameter. A part of this thread was applied endwise to the lower blue part of the flame of the candle without the use of the blowpipe. The extremity immediately became white hot, and formed a globule. The glass was then gradually and regularly thrust towards the flame, but never into it, until the globule was sufficiently large. A number of these were made; and being afterwards examined, by viewing their focal images with a deep inagnifier, proved very bright, perfect, and round. This, as the ingenious author observes, may prove an acceptable piece of information to those eminent men (and there are many such), whose narrow circumstances, or remote situations, are obliged to have recourse to their own skill and ingenuity for experimental implements. LENSES, GROUND, are such as are ground or rubbed into the desired shape, and then polished. Different shapes have been proposed for lenses; but several practical writers on optics have shown that, after all, the spherical is the most practically useful. By many of the methods of grinding, however, the artificer, with his utmost care, can only produce an approximation to a truly spherical figure; and, indeed, gentlemen have, for the most part, nothing to depend on for the sphericity of the lenses of their telescopes, but the care and integrity of the workmen. In the forty-first volume of the Transactions of the Royal Society of London, a machine is described by Mr. Samuel Jenkins, which, as it is contrived to turn a sphere at one and the same time on two axes, cutting each other at right angles, will produce the seg ment of a true sphere merely by turning round the wheels, and that without any care or skill in the workmen. This machine is described at page 239, vol. ii. Dr. Gregory's Mechanics. The following directions for grinding and polishing lenses, are given by Dr. Brewster, in the second volume of his edition of Ferguson's Select Lectures. 66 Having fixed upon the proper aperture and focal distance of the lens, take a piece of sheet copper, and strike upon it a fine arch, with a radius equal to the focal distance of the lens, if it is to be equally convex on both sides, or with a radius equal to half that distance, if it is to be plano-convex, and let the length of this arch be a little greater than the given aperture. Remove with a file that part of the copper which is without the circular arch, and a convex gage will be formed. Strike another arch with the same radius, and having removed that part of the copper which is within it, a concave gage will be obtained. Prepare two circular plates of brass, about of an inch thick, and half an inch greater in diameter than the breadth of the lens, and solder them upon a cylinder of lead of the same diameter, and about an inch high. These tools are then to be fixed upon a turning lathe, and one of them turned into a portion of concave sphere, so as to suit the convex gage; and the other into a portion of a convex sphere, so as to answer the concave gage. When the surfaces of the brass plates are turned as accurately as possible, they must be ground upon one another, alternately with flour emery till the two surfaces exactly coincide, and the grinding tools will then be ready for use. Procure a piece of glass, whose dispersive power is as small as possible, if the lens is not for achromatic instruments, and whose surfaces are parallel; and by means of a pair of large scissars or pincers, cut it into a circular shape, so that its diameter may be a little greater than the aperture of the lens. After the roughness is removed from its edges by a common grindstone, it is then to be fixed with black pitch to a wooden handle of a smaller diameter than the glass, and about an inch high, so that the centre of the handle may exactly coincide with the centre of the glass. "When the glass is thus prepared for use, it is then to be ground with fine emery upon the concave tool, if it is to be convex, and upon the convex tool, if it is to be concave, To avoid circumlocution, we shall suppose that the lens is to be convex. The concave tool, therefore, which is to be used, must be firmly fixed to a table or bench, and the glass wrought upon it with circular strokes, so that its centre may never go beyond the edges of the tool. For every six circular strokes, the glass should receive two or three cross ones along the diameter of the tool, and in different directions. When the glass has received its proper shape, and touches the tool in every point of its surface, which may be easily known by inspection, the emery † is to be washed away, and finer kinds successively substituted in its room, till by the same alternation of circular and transverse strokes, all the scratches and asperities are removed from its surface. After the finest emery has been used, the roughness which remains may be taken away, and a slight polish superinduced by grinding the glass with pounded pumice-stone, in the same manner as before. While the operation of grinding is going on, the convex tool should, at the end of every five minutes, be wrought upon the concave one for a few seconds, in order to preserve the same curvature to the tools and the glass. When one side is finished off with pumice-stone, the lens must be sepa rated from its handle by inserting the point of a knife between it and the pitch, and giving it a gentle stroke. The pitch which remains upon the glass may be removed by When the focal distance of the lens is to be short, the surface of the piece of glass should be ground upon a common grindstone, so as to suit the gage as nearly as possible; and the plates of brass, before they are soldered on the lead, should be hammered as truly as they can into their proper form. By this means much labour will be saved, both in turning and grinding. Emery of different degrees of fineness may be made in the following manner: Take five or six clean vessels, and having filled one of them with water, put into it a considerable quantity of flour emery, Stir it well with a piece of wood, and after stacErg for five seconds, pour the water into the second vessel. After it has stood about twelve seconds, pour it out of this into a third vessel, and so os with the rest; and at the bottom of each vessel will be found emery of different degrees of fineness, the coarsest being in the first vessel, and the finest in the last. |