LUJN 



LUN 



LUMBAGO, in medicine, a rheuma- 

 tic affection of the muscles about the 

 loins. 



LUMBRICUS, in natural history, the 

 earth-worm, a genus of the Verrnes Intes- 

 tina : body round, annulate, with general- 

 ly an elevated fleshy belt near the head, 

 mostly rough, with minute concealed 

 prickles, placed longitudinally, and fur- 

 nished with a lateral aperture. Gmelin 

 has enumerated sixteen species, of which 

 we shall notice the following : L. terristris, 

 dew-worm ; body red, with eight rows 

 of prickles ; there are two varieties, one 

 being as long again as the other. It in- 

 habits decayed wood, and the common 

 soil, which, by perforating, it renders tit to 

 receive rain ; devours the cotyledons of 

 young plants, and wanders about in the 

 night ; is the food of rnoles, and various 

 birds. It is said to have about one hun- 

 dred and forty rings ; head taper ; n^uth 

 at the end, round ; fore-part of the worm 

 cylindric, the rest depressed; at about 

 one third of its length is a prominent an- 

 milated belt ; on each side of the belly a 

 row of minute spines, distinguishable 

 only by the touch, but which are of aid 

 to their motion. L. marinus, the lug; 

 back with two rows of bristly tubercles. 

 This species inhabits the shores of the 

 sea, where it buries itself deep in the 

 sand, leaving a little rising with an aper- 

 ture on the surface, and is used as a bait 

 for fish. Body pale red, round and an- 

 nulate, with greater and lesser rings ; the 

 first prominent, with two opposite tufts of 

 short bristles on each; the lower part 

 smooth. L. vermicularis, body white, with 

 two rows of prickles ; inhabits the wet 

 and decayed trunks of trees, and among 

 moist leaves, moving very expeditiously 

 in humid places, but twisting itself up in 

 dry ones : body polished, glabrous. L, 

 edulis, bod}' whitish flesh-coloured ; sub- 

 clavate behind, dilated and papillous be- 

 fore ; mouth terminal, and surrounded 

 with a very viliose rim or wrinkle. It in- 

 habits the sandy shores of the islands in 

 the Indian ocean ; nearly a foot long, and 

 about as thick as a goose quill ; buries it- 

 self about a foot or more deep in the sand, 

 and is eaten by the Chinese : the rings 

 between the villous part and the hinder 

 end 278, and separated by an annular 

 stria ; the hind part bulbous, with a dou- 

 ble papilla; the fore-part beset with nu- 

 merous flesh-coloured ones, disposed in 

 transverse rows. 



LUNA, in astronomy, the moon. See 

 MOON. 



LUNA, among chemists, signifies silver, 

 See SILVER. 



LUNAR, something belonging to the 

 moon -, thus we say lunar month, lunar 

 year, lunar dial, lunar eclipse, &c. 



LUNAR caustic^ is the old name for 

 nitrate of silver, a very powerful caustic, 

 much used in medicine. It is also called 

 " Lapis Infernalis," by surgeons. 



LUNARIA, in botany, honesty, a genus 

 of the Tetradynamia Siliculosa class and 

 order. Natural order of Siliquosx or 

 Oucifbrmes. Essential character : sili- 

 cic entire, elliptic, compressed, flat, pe- 

 dicelled ; valves equal, and parallel to the 

 partition, flat ; calyx with bugged leaflets. 

 There are three species, viz. the perenni- 

 al, annual, and Egyptian honesty. 

 LUNATIC. See IDIOT. 

 LUNATION, the period or time be- 

 tween one new moon and another : it is 

 also called the synodical month, consist- 

 ing of 29<i 12'' 44' 3" Hods; exceeding 

 the periodical month by 2 d 5 h 0' 55". 



LUNE, in mathematics, is a geometri- 

 cal figure, in form of a crescent, termi- 

 nj<ted by the arcs of two circles that in- 

 lers^ct each other within. Though the 

 quudtature of the whole circle has never 

 been ejected, yet many of its parts have 

 been squared. The first of these partial 

 quadratures was that of the lunula, given 

 by Hippocrates, of Scio, or Chios ; who, 

 from being . shipwrecked merchant, 

 commerced geometrician. But although 

 the quadrature of the lune be generally 

 ascribed to Hippocrates, yet Proclus ex- 

 pressly says, * was found" out by Oenopi- 

 das of the same place. The lune of Hip- 

 pocrates is this : let A B C, Plate IX. 

 Miscel. fig. 7, be a hmi-circle, having its 

 centre E; and A D C * quadrant, having 

 its centre F ; then the figure AB C D A, 

 contained between the arcs of the semi- 

 circle and quadrant, is his lune ; and it is 

 equal to the right-angled triangle A C F, 

 as is thus easily proved. Since A F 2 = 

 2 A E% that is, the square of the radius 

 of the quadrant equal to (iouble the 

 square of the radius of the senu- c ircle ; 

 therefore the quadrant-area, AbCFA, 

 is s= the semi-circle of A B C E A ; from 

 each of these take away the common 

 space ADCEA, and there remains the 

 triangle A C F = the lune A B C D A. 

 Another property of this lune, which is 

 the more general one of the former, is, 

 that if F G be any. line drawn from the 

 point F, and A H perpendicular to it ; 

 then is the intercepted part of the lune 

 A G I A = the triangle A G H, cut off by 



