LEN
A Letts, one of whofe Surfaces is Convex, and the other Concave, is called xMemfcusj the Properties of which fee under Mem/cm. See alfo tie Theory of Letts'! demon- /hated under RefraSitm, and the Application thereof un- der Micro/cope, Telefcope, Burnitsg-Glafs, Bens, ckc.
Some confine Lens's within the Diameter of five or fix Lines, and will have fuch as exceed that Diameter, call'd Lenticular Glaffes. Lens's are diftinguifh'd with regard to their Preparation into ground and blown: blown Lens's are little Globules of Glafs melted in the Flame of a Lamp or Taper : (fee Micro/cope) but the Figure of thefe M fcldom exafl ; befides that the Smoke of the Lamp cleaves to the Surface in melting : on both which accounts they come fliort of the Clcarnefs of thofe that are ground, or turned and polifli'd in the Lathe, in little Copper Ba- tons or Dimes. The Secret is now found of making thefe cxquifitely fmall, fo as fome of 'em don't exceed'in Dia- meter the fixth part of a Line, which are found to mag- nify Objefls feveral Millions of times.
_ The Manner of grinding Lens's : A little Piece of Copper is cemented to the End of the Arbor of a Lathe, and turned, till ir form a Dim or Bafon of the Diameter of the Letts required. Then a Piece of clear Glafs is cemented on one of its flat Sides to the end of a little Mandrel with black Spanifi Wax, and thus ground, on the Side not ce- mented, on a Grindftone, with Water, till it have nearly acquired a Convex Figure. 'Tis finilhed in the Lathe, by turning it in the Bafon, with fine wet Sand, or Free-ftone. fcSeeBa/oH.) The Free-ftone mufi be often repeated frefh,' till .the Letts appear very round; when it is come to that I omt, they ceafe to take any fre/h Stone, but continue to turn it in the Bafon, till the Remains of the Sand be be- come fo fine as to have polidied it. This, they perceive, when, upon wiping it, the Image of the Window of the Place is feen painted on its Surface ; if it don't, 'tis wet- ted in Water without any Sand, and turned till it have got a Polilh. The Bafon is then covered, within-fide, with two or three Folds of Linnen, and the Polifti finilhed with Putty, or TrifoJy of Venice fteeped in Water. 'Tis known to be perfectly polilhed, when, viewing it with a Magnifier, there appear no Traces of the Sand. The Cement is then broke off, and the Side polifhed, cemen- ted ; to work and grind the other as before, till the Edges of the Lensbe become fharp, and it be perfectly polilhed on either fide. When finished, 'tis warned in Spirit of Wine, to takeoff all Remains of the Wax. See Micro) cape. LENT, Quadragefima, or Quarantine, a Time of Mor- tification, confiding of the Space of forty Days, wherein thofe efpecially of the Romifh Church are enjoined to faft, in Commemoration of our Saviour's miraculous Falling fo long in the Defarr, and by way of Preparation for the Feail oT Eafter. In the antient Latin Church, Lent only confifted of 3« Days. In the IXth Century, to come fomewhat nearer the Miracle, fome took upon them to add four Days more, which, in time, became a general Practice ; tho the Church of Milan is faid dill to take up with the antient 30".
According to St. Jerom, St. Lett, St. Augtijitne, and 0- thers, Lent mud have been inftituted by the Apollles. Their way of Reafoning is thus: Whatever is generally received throughout the whole Church, and whofe In- ftitution we don't find in any Council, mull be cfteemed to have been eftabli/hcd by the ApolHes. Now fuch, they fay, is the Faft of Lent. Its Inftitution is not fpoke of in anyCouncil, but manyof the antient Councils, par- ticularly that of Nice, that of Laodicea, &c. and fome of the Fathers, particularly Tertullian, fpeak of it as a thing of iome Handing. The Reformed generally hold Lent to be a fupcrftitious Inftitution, fet on foot by fome vain En- thufialls, who durft undertake to ape the Miracles of Je- fus Chrift, as in effeft it appears to have been from a Paf- fage of Irenxus, quoted by Etifeb'ms. Some will have it to have been firft introduced by Pope Telefphorus, in the lid Century.; others, who own that there was a kind of Abfti- nence obferved in the antient Church before Eafter, yet contend that it was voluntary, and was never enjoined by any Law till the Hid Century.
There was fome Difference between the Practice of the Greek and theLatitt Church as to the Bufinefs of Lent ; the Greeks beginning it a Week fooner, but at the fame time allowing more Days of Intcrmiffion than the Latins -. thofe who held it feven Weeks, did not faft on Saturdays, as thofe who obferved it but fix did.
The antient Latin Monks had three Lents ; the Grand Lent before Eafter ; another before Chriftmas, call'd, The Lent of St. Martin ; and a third after Whitfunday, call'd that of St. John Baftift : each of which confifted of forty Days. The Greeks, befides that before Eafter, obferved four others ; that of the slpoftles, of the JJJumptiott, of Chriftmas, and of the Transfiguration ; but they reduced each of them to the fpace of feven Days. The Jacobites added a fifth, which they call The Repentance of Nine-
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veB , and the Maromtes a fixth, call'd The Exaltation of, be
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The forty Days in Lent, fay fome, are obferved in re- membrance of the forty Days wherein the World was drowned ; others of the forty Years wherein the Setts wandered in theDefart ; of the forty Days allowed Ntne- veb tor Repentance 5 the forty Stripe's by' which Malefac- tors were to be corrected ; the forty" Days filled by Mo- fesex the receiving of the Law ; thefortv Days failed by Ettas-, or the forty Days failed by our Saviour. 01 ■ r T L G ?' a fteckI y or fcurvy Eruption upon the rVV,", , c, P eC!all y asis common to Women in the time of Child-bearing. Authors dillinguiih this Eruption into leveral kinds.
LENTIL, the Name of a Weight among the oldKo- mnns. It was the hundred and eighth Part of a Drachm. A Ze«j/and an half made a Grain. The Word is aDi- minutiveof Lens.
LENTISCUS, the Wood of a Tree of the fame Name, of fome Ule in Phyfic ; it is aftringent and fortifying, and much ufed for Tooth-Picks. It contains a kind of Gum, or rather refinous Pitch, much like Mallic, or perhaps theMaftic itfelf or Incenfcof Perfta, fo highly commend- ed by Strabo. The Lentifcus has nearlv the fame Proper- ties with the Sikh*,.,, but has more of the Turpentine in it, andfometimes paries by Urine.
LEO, Lion, the fifth of the twelve Signs of the Zo- diack. This the Allrologers account a hot dry Sign, and the Houfe of the Sun. The Antients gave it 27 Stars, befides 8 lnformes: Kcflc- gives it 40, and Bayer 4, 5 two whereof are of the firft Magnitude, two of the fe- cond, five of the third, Ei?c. See Star..
Cor Leonis, the Lion's Heart, one of the moll confidera- ble Stars in the Heavens. See Star
LEONT1CA, the Name of a Feaft or Sacrifice cele- brated among the Antients, in honour of the Sun. They were called Leontica, and the Priefts who officiated at them Leoni, in regard they reprefented the Sun under the Figure of a Lion radiant, bearing a Tiara, and griping in his two fore Paws the Horns of a Bull, who ilruggled in vain to difengagc himfelf. The Critics are extremely divided about this Feaft, fome will have it to be anniver- fary, and make its Return not in a Solar, but a Lunar Year ; but others hold its Return to be more frequent, and give Inftances where the Period was not above zio Days. The Ceremony was fometimes alfo call'd Mithria- ce, Mithra being the Name of the Sun among the antient Ferfians. There was always a Man facrificed at thefe Fcafts till the time of Hadrian, who prohibited it by a Law. _ Commodus introduced the Cuflom afrefti, after whofe time it was again exploded.
LEONTINE,;,, Poetry, a kind of Verfes which rhyme at every Hemiflic, the middle always chiming to the end ; of which kind we find feveral antient Hymns, Epi- grams, Prophecies, Syc. For inftance, Maretus fpe'akine of the Poetry of Lorenzo Gambara of BreJJb, fays, Brixia, veftrat'is merdofa Volumina Vatls, Non fum nojiratets tergere digna Nates. The following one is from the School of Salerna ;
Vt Vites Pcenam de potibus incipe Ctenam. The Origin of thcWord is fomewhat obfeure, Fafquier de- rives it from one Leon-inns, or Leon'ms, who excelled in this way, anddedicated feveral Pieces to Pope Alexander \l\. Others derive it from Pope Leo, and others from the Name of Lion, as being the lofticll of all Verfes. M. Fau- chet makes the Leonine Rhyme the fame with what the French call The Rich, and we The Double Rhyme ; i. e. where two Syllables have the fame Otthography, Accen- tuation, and Pronunciation with two others.
LE ROY LE VEUT. By thefe Words the Royal Af- fent is fignified by the Clerk of the Parliament to pub- lic Bills ; to private Bills this Aflent is expreffed by frit fait comme il eft Deftre.
LE ROY S'ADVISERA. By thefe Words to a Bill, prefented to the King by his Parliament, are underftood his abfolute Denial of that Bill in a more civil way; and the Bill thereby becomes wholly null and void.
LEPJDOIDES, in Anatomy, the Name of the fcaly Suture of the Cranium, from the Greek /.sot, Scale, and eftfl©-, Form, Figure.
LEPRA, Leprofy, a foul contagious Difcafe, feated in the Cuticle or Surface of the Skin, ariiing, as moll other cutaneous Difeafesdo, from thin fait Humours, thrown off from the Blood, and arrcfted by the Denfity and Clofenefs of the Cuticula. This Diftemper has been much more frequent in former Times than at prefent, and much more in the hot Countries of the Eaft, particularly among the Jews, than among us ; for the Salts which,
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