LUN 
decayed wood, and the common soil, which, 
by perforating, it renders fit to receive 
rain ; devours the cotyledons of young 
plants, and wanders about in the night ; is 
the food of moles, hedge-hogs, and various 
birds. It is said to have about one hun- 
dred and forty rings ; head taper ; month 
at the end, round ; fore-part of the worm 
cylindric, the rest depressed ; at about one- 
third of its length is a prominent annnlated 
belt; on each side of the belly a row of mi- 
nute 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 aperture on the surface, and is used as a 
bait for fish. Body pale red, round and 
annulate, with greater and lesser rings ; the 
first prominent, with two opposite tufts of 
short bristles on each ; the lower part 
smooth. L. verinicularis, body white, with 
two rows of prickles ; inhabits the wet and 
decayed trunks of trees, and among moist 
leaves, moving very expeditiously in liumid 
places, but twisting itself up in dry ones : 
body polished, glabrous. L. edulis, body- 
whitish flesh-coloured ; subclavate behind, 
dilated and papillous before ; month ter- 
minal, and surrounded with a very villose 
rim or wrinkle. It inhabits the sandy 
shores of the islands in the Indian ocean ; 
nearly a foot long, and about as thick as a 
goose quill ; buries itself 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 double papilla ; the fore-part beset with 
numerous 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 ni- 
trate of silver, a very powerful caustic, 
much used in medicine. It is also called 
“ Lapis Infernalis,” by surgeons. 
LUN-ARIA, in botany, honesty, a genus 
of the Tetradynamia Siliculosa class and or- 
der. Natural order of Siliquosae, or Cruci- 
formes. Essential character : silicle en- 
tire, elliptic, compressed, flat, pedicelled ; 
valves equal, and parallel to tlie partition, 
LUN 
flat; calyx witli bagged leaflets. There 
are three species, viz. the perennial, 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, consisting 
of 29'* 12*“ 44' 3''T1-3ds ; exceeding the pe- 
riodical month by 2'* S'* O' 55 '. 
LUNE, in mathematics, is a geometrical 
figure, in form of a crescent, terminated by 
the arcs of two circles that intersect each 
other within. Though the quadrature of 
the whole circle has never been effected, 
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 a ship- 
wrecked merchant, commenced geometri- 
cian. But although the quadrature of the 
lune be generally ascribed to Hippocrates, 
yet Proclus expressly says, it was found out 
by Oenopidas of the same place. The lune 
of Hippocrates is this: let A B C, Plate 
IX. Miscel. fig. 7, be semi-circle, hav- 
ing its centre E; and ADC a quadrant, 
having its centre F; then the figure, 
A B 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 P, as is thus easily proved. Since A 
= 2 A E^, that is, the square of the radius 
of the quadrant equal to double, the square 
of the radius of the semi-circle ; therefore 
the quadrant-area, A D C F A, is = the se- 
mi-circle of A B C E A ; from each of these 
take away the common space A D C E A, 
and there l emains the triangle A C F = the 
lune A B CD A. Another property of this 
lune, which is the more general one of the 
former, is, that if FG be any line draivn 
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 the chord line A G ; or, in general, that 
the small segment, AKGA, is equal to 
the tri-lineal AIHA. For, the angle 
A F G being at the centre of the one circle, 
and at the circumference of the other, the 
arcs cut off AG, A I are similar to the 
wholes A B C, A D C, therefore the small 
segment AKGA is to the semi segment 
A I H, as the whole semi-circle A B C A to 
the semi-segment or quadrant AD C F, that 
is, in a ratio of equality. Again, if A B C 
(fig. 8) be a triangle, right-angled at C, 
and if semi-circles be described on the 
three sides as diameters ; then tlie triangle 
T (ABC) is equal to the sum of the two 
