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the fame parts of the branches from whence the leaves arlfe j there are alfo feen to arife other very flender and very fhort ftalks which bear fmall capfules, within which is enclofed the flower and afterwards the feed. The flowers are placed in feveral lodgments in this fhell, and are compofed of ftamina and piftils, but have no petals j the piftils are va- rious in number in the different flowers, from three to eight, the ftamina are always very minute and very numerous. Memoirs Acad. Scien. Par. 1740.
Plukenet has defcribed this plant a little differently from this writer, but the difference feems only owing to this, that Plukenet defcribed one he found in deep water, whereas Mr. Juflieu formed his account from the more ordinary and perfect appearance of the plant in fhallow water, where alone it ripens its flowers and feeds. We have it not in England fo far as is yet known, but it is common in the Eaft and Weft Indies and in France. LEMNIAN garth, Lemnia terra, a kind of bole or fine earth ufed in medicine, of which there are three fpecies ; the white, the yellow, ari'd the red, but the red is mod ufed. The characters by which they may be diftinguifhed from all other earths of the fame colours are thefe. Red lemnian earth is a denfe compact earth of a clofe firm texture and pale red colour, and of a fmooth and even, but not glofly furface. It does not break readily between the fingers, nor at all ftains the hands, is not readily diffufible in water, melts flowly in the mouth, is very aftringent to the tafte, and when in its native ftate is always fomewhat harfh and gritty between the teeth ; for*what we find of it that is perfectly pure, and free from fand, is fuch as has been wafhed and feparated from it, all the genuine earth naturally containing fome. It adheres firmly to the tongue, raifes a flight effervefcence with aqua fortis, and fuffers very little change in a moderate fire. HiWs Hire, of Foflils, p. 13. This is dug in the ifland of Lemnos, and in no other place fo far as is yet known ; and the fine and true earth only in one pit, which is opened once every year and no oftner, with great folemnity ; and the earth, fuppofed fufHcient for the year's demand, is taken out and fold to the merchants ; fomc fealed with various figures, other quantities unfealed ; but, what is there bought unfealed is generally formed into fmall manes, and fealed before it is offered to fale in Europe, the druggifts always expecting to find lemnian earth fealed. This is a very valuable earth, but is too often adulterated, frequently by the Turks upon the fpot, either by mixing it with other earths, or another earth alone being fold in its place, but more frequently in Europe, where every whole- sale dealer knows how to make a compofition of 'our own clays, and properly tinge them with ochre, and afterwards give an impreflion refembling that of the genuine. Ibid. . Tl)e white lemnian earth is a fine bole of a very pure white, but of a fomewhat lax texture, and lefs weighty than the other boles ; it appears of a tolerably fmooth furface, but feels fomewhat dufty on rubbing; it fcarce at all ftains the fingers in handling, very eafdy crumbles to pieces, adheres ftrongly to the tongue, and melts freely in the mouth, but like the red, leaves a fandy harfhnefs between the teeth this makes no effervefcence with acids. It is dug in the ifland of Lemnos, and ufed in the German fhops as an aftringent and fudorific. The antients knew this kind, but never ufed it in medicine, efteeming the other fuperior, but they employed it as the cimolia about cloaths. Hill's Hift. of
Foflils, p. 2.
The yellow lemnian earth is a very valuable earth, common in the fhops, and more than all the other fubftances of this kind fubject to be counterfeited.
It is a very pure and fine earth, of a lively florid yellow, of a clofe compact texture and fmooth furface, confiderably hard, and not at all flaming the fingers in handling. It flicks firmly to the tongue, and melts pretty readily in the mouth, leaving not the leaft harfhnefs between the teeth. and does not ferment with acid menftrua. It is counter- feited two ways ; the one by a yellow ochre, which may be difcovered by its flaming the hands, and the other by a yellow clay ; but this is eafily known by its want of the true florid colour, and having all the characters of a clay not a bole. The genuine is found only in the ifland of Lemnos, and is the ffratum next above the red. It is efteemed a fudorific, aftringent and vulnerary. Hill's Hift. of Foflils, p. 8.
LEN./EA, Aiiv«<a, in antiquity, a feftival of Bacchus, fur- named ienaus from Xw#* i. e. a vine prefs. Befides the ufual ceremonies at'feafts facred to this God, it was remark- able for poetical contentions, and tragedies acted at this time. Potter, Archaeol. 1. 2. c. 20. TV I. p. 412.
LENGTH, in the manege — To fajfage a horfe upon his own length, is to make him go round in two treads, at a walk o trot, upon a fpot of ground fo narrow, that the horfe' haunches being in the center of the volt, his own length is much about the femi-diameter of the volt ; the horfe ftill working between the two heels, without putting out hi croupe, or going at laft fafter or flower than at firft. See the article Volt.
LENS (Cycl.) — In the Philofophlcal Tranfadtions we have the Suppl. Vol. I.
figure of a machine for grinding lenfes fphcrlcally. It is a contrivance to turn a fphere at one and the fame time on two axes, interfering each other at right angles, with an equal velocity and preffiire on each. See the Tranfactions, N° 459. Sea. 1. Lens, the lentil, in botany, the name of a genus of plants, the characters of which are thefe. The flower is of the pa- pilionaceous kind, and from the cup there arifes a piftii, which finally becomes a fhort rod, containing orbicular feeds, and thicker toward the middle than at the edges. The fpecies of lentil enumerated by Mr. Tournefort are thefe. 1. The common lentil with brownifh red feeds. 2. The common lentil with pale yellow feeds. 3. The common lentil with fpotted jeeds. 4, The common lentil with black feeds. 5. The greater lentil; and 6. The Hungarian lentil, with taller ftalks and perennial roots. Tourn. Inft. p. 390. UENTAfebris. See the article Fever. LENTES lapidea, fojfile lentils, the name given by many- writers to a very remarkable foflile fubftauce, ufually found immerfed in hard ftones, and of a roundifh but flatted fhape, refembling not unaptly a pea or lentil flatted by preffurc. They generally lie in great quantities in the fame mafs of ftone ; and are of a very different appearance, when their fides or ends are feen from that which they exhibit, when their flat furfaces come in view. They are generally fup- pofed to be lentils petrified and bedded in ftone, and as their fides come in view in fome parts of the maffes, they are not perceived to be a part of the fame fubftances, but are called the remains of feeds of other plants, and the whole ftone is ufually named lapis frumentarius.
We are not to fuppofe, that fo foft a body as the lentil feed, or a common ^w, could be eafily petrified and preftirved in its own form in ftone; fince if thefe foft fubftances were readily capable of fuch a change, they are fo very common in their recent flate, that they mull be expected to be found in this fojfilc condition very frequently alfo, and in great variety ; this, however, is not the cafe. But this improbability is not all the reafon we have to conjecture, that thefe are not what they are vulgarly fuppofed to be, that is, fojjile feeds ; for a firicter examination of the things themfelves proves this to be impoflible. Seeds, and other fuch things, are of fome determinate growth ; the fize of which we know, and are well acquainted with their internal ftrudture, which is only a farinaceous matter contained in a thick fuperficial fkin or covering.
On the contrary, thefe fojfils, when examined, prove to be of various fizes, from the minuteft fpeck viable to the eye, to near an inch in diameter, a fize that no lentil could be fuppofed to arrive at. They are of two kinds ; the one convex on both fides, the other convex on one fide only, and plain on the other. The firft are thickeft in the mid- dle, and gradually le/len in thicknefs all round, till they terminate in a thin edge; the others are juft like the halves of thefe, when fplit horizontally. Thofe which are con- vex on both fides, have ufually feveral crooked lines, rifing from the umbilicus on each fide, and tending toward the circumference ; and the flat ones, have ufually on the flatted fide, a number of concentric circles, furrounding the um- bilicus, and one another to the edge. When thefe are bro- ken they are found to confift of a number of cafes, or coats, one within another, all of the fame fhape with the outer one ; and fome of them are ftriated or made up of tranfverfe fibres j they are plainly of animal origin, though they differ from all the parts of animals hitherto known. Woodward's Cat. Foff. Vol. 2.
Dr. Woodward, in one place, fuppofes them to have been the loofc bones which are found in the heads of fome fea fifties, and are fuppofed to ferve for hearing ; but that they belong to fome fifh at prefent unknown, or that has not been yet examined in this particular : there is, however, ano- ther much more probable opinion, which he mentions after- wards, that they may have been opercula of fhell fifties, of the nature of the umbilicus veneris, of which the fifties we know afford us a great variety ; and the many others we are yet unacquainted with, may furnlfli numbers of other kinds very different from all we do know. Thefe bodies are found in a hard greyifh ftone, and fome of the large ones which are flatted on one fide, give great rea- fon to judge that they are of this origin, as fome of the large ones have on the flat fide, a reddifh line beginning at the center, and thence continuing in a fpifal form, for eleven or twelve turns, till it reaches the edge of the ftone. This is exactly the formation and lineation of the common um- bilicus veneris, only that it has fewer fpires. The ftone called by authors lapis numifnmlis, is generally allowed to be of the nature of thefe opercula, and this differs very little from thefe large lentes lapidete, as they arc called. LENTISCUS, the lentijk or majlic tree, in botany, the name of a genus of trees, very nearly allied to the terebinthus or turpentine tree in its characters, but differing in that the leaves are pinnated ; but there is no fingle leaf to terminate the end of each compound one. Town. Inft. p. 580. The fpecies of the lentijk enumerated by Mr. Tournefort 1 15 I are
