PLA 



PLA 







camp, a large place at the head of the 

 camp for the army to be ranged in and 

 drawn up in battalia. There is also a 

 place for each particular body, troop, or 

 company to assemble in. 



PLACENTA. See MIDWIFERY. 



FLAGIANTHUS, in botany, a genus 

 of the Monadelphia Dodecandria class 

 and order. Essential character : calyx 

 five cleft ; petals five, two approximating, 

 remote from the other three ; berry. 

 There is but one species, viz. P. divarica- 

 tus, a native of New-Zealand. 



PLAGIARY, in philology, the purloin- 

 ing another person's works, and putting 

 them off for a man's own. 



PLAGUE. Any infectious distemper 

 in foreign countries may be declared the 

 plague, by the King's proclamation. 

 And there are several very salutary regula- 

 tions by our statute law for the perfor- 

 mance of quarantine, in order to prevent 

 the extending of infection. 



PLAIN table, in surveying, a very sim- 

 pie instrument, whereby the draught of a 

 field is taken on the spot, without any 

 future protraction. It is generally of an 

 oblong rectangular figure, and supported 

 f by a fulcrum, so as to turn every way by 

 means of a ball and socket. It has a 

 moveable frame, which serves to hold 

 fast a clean paper ; and the sides of this 

 frame, facing the paper, are divided into 

 equal parts every way. It has also a box 

 with a magnetical needle, and a large in- 

 dex with two sights ; and, lastly, on the 

 edge of the frame, are marked degrees 

 and minutes. See SURVEYING 



PL AIN number, is a number that may 

 be produced by the multiplication of two 

 numbers into one another : thus 20 is a 

 plain number produced by the multiplica- 

 tion of 5 and 4. 



P i, AIN problem, in mathematics, is such 

 a problem as cannot be solved geometri- 

 cally, but by the intersection either of a 

 right line and a circle, or of the circum- 

 ferences of two circles : as given the 

 greatest side, and the sum of the other 

 two sides of a right-angled triangle, to 

 find the triangle, as also to describe a 

 trapezium that shall make a given area of 

 four given lines. Such problems can on- 

 ly have twa solutions, because a right 

 line can only cut a circle, or one circle 

 cut another in two points. 



PLAIN, in heraldry, sometimes denotes 

 the point of the shield, when couped 

 square ; a part remaining under the 

 square, of a different colour or roetal 

 from the shield. This has been sometimes 

 used as a mark of bastardy, and called 



champaigne : for, when the legitimate 

 descendants of bastards have taken away 

 the bar, fillet, or traverse borne by their 

 fathers, they are to cut the point of the 

 shield with a different colour called 

 plain. 



PLAISE. SeePLEURONECTES. 



PLAN, in general, denotes the repre- 

 sentation of something drawn on a plane : 

 such are maps, charts, ichnographies, &c. 

 See MAP, CHART, &c. 



The term plan, however, is particular- 

 ly used for a draught of a building, such, 

 as it appears, or is intended to appear, 

 on the ground ; shewing the extent, di- 

 vision, and distribution of its area, or 

 ground-plot, into apartments, rooms, pas- 

 sages, &c. A geometrical plan is that, 

 wherein the solid and vacant parts are 

 represented in their natural proportions. 

 The raised plan of a building, is the same 

 with what is otherwise called an eleva- 

 tion, or orthography. A perspective plan, 

 is that exhibited by degradations, or di- 

 minution*, according to the rules of per- 

 spective. 



PLANAttIA, in natural history, a ge- 

 nus of the Vermes Intestina class and 

 order. Generic character : body gelatin- 

 ous, flattish, with a double ventral pore ; 

 mouth terminal. There are about fifty 

 species, divided into six sections, distin- 

 guished by the number of their eyes : A 

 without eyes : B with a single eye : C 

 with two eyes : D with three eyes : E 

 with four eyes : and F with numerous 

 eyes. Of the first division we may notice, 

 P. quadrangularis ; body pale, ovate, very 

 sharp-pointed before, and winged with 

 small curled longitudinal membranes. 

 It is found in Europe in ditches among 

 duck-weed j very soft, pellucid, of a 

 changeable form, and moves like a slug, 

 leaving a slime on the bodies it passes 

 over; when it meets another animal it. 

 draws itself in like a snail. 



Of the third division we have a species 

 which is very common in Pennsylvania, in- 

 habiting running waters, large creeks, &c. 

 It may be found by turning up the stones 

 which lie in the water, and looking atten- 

 tively on their under surface. We have- 

 named this species P. triangularis ; bo- 

 dy pale, linear, rounded behind, head 

 triangular, angle in front acute, lateral 

 acute angles extending rather beyond 

 the line of the body, eyes round, black, 

 conspicuous, placed about the middle 

 of the head, and partly surrounded each 

 with a whitish mark or lunule; this, how- 

 ever, is sometimes obsolete. It trails 

 along with a slow but regular gait, ovt;i" 



