PAR 



537 



PAR 



bercles ; also to leaves covered with 

 fleshy dots or points. 



PAP'PUS. Down, from jr;r;re?. 1- In 

 anatomy, the hair on the middle of the 



chin. 2. In botany, the seed-down ; 



the feathery appendage which crowns 

 many seeds that have no pericarp, and 

 which originates in a partial calyx, 

 which crowns the summits of the seeds, 

 as of the dandelion, goafs-beard, &c. By 

 some botanists the term is generally used 

 for the feathery crown of seeds furnished 

 with a capsule, and also for a similar ap- 

 pendajse to the base of some seeds and the 

 sides of others. 



PAP'CLOSE, Lat. papulosm. Pimpled. 

 Applied to leaves, &c., which are covered 

 with vesicular dots, or minute blisters. 



PAPYROG'RAPHY, from jrairyjo? , paper, 

 and yc*w, to write. A method of taking 

 impressions from a sort of pasteboard, 

 covered with a calcareous substance, ex- 

 actly as from the stone in lithographic 

 printing. The prepared pasteboard is 

 also called lithographic paper. 



PAPY'RUS, srauryif. The paper-plant. 

 A genus. TriandriaSlonogynia. There 

 are two species : the P. odoratus, of the 

 "West Indies ; and the renowned P. anti- 

 quorum of Egypt, a stately reed or rush, 



the inner bark of which was used by the 

 ancients for writing upon ; or rather foi 

 making paper to write upon ; and latterly 

 indeed, for all the common purposes to 

 which paper is at present applied. Pliny 

 in his Hist. Nat. lib. xiii., c. 11, 12,13, de 

 scribes the process of making paper from 

 the papyrus, and enumerates the various 

 kinds that were composed, fivm tli 

 coarsest, which was used like our brown 

 paper for packing, to the finest and mos 

 expensive. The chief seat of the mauu 

 facture was at Alexandria. 



PAR. A Latin word for equal. Use< 

 in comnurct, to denote that two things 



ire of equal value ; and in money-affair*, 



he equality of one kind of money or pro- 



Drty with another. 



PA'RA. A Turkish coin of copper and 

 Iver, very small and thin, and worth the 



brtieth part of a piastre. 

 PARAB'OLA. riaaSoAfj, from caa 



gainst, and (3*XA, to throw. A conic 

 section, formed 

 by a cone being 

 cut by a plane, 

 which is paral- 

 lel to a tangent 

 plane, to the 

 curved surface 

 of the cone. 

 Thus V is the 

 vertex ot the pa- 

 rabola m Vo; the 

 right line Vn is 

 the axis, and 

 any line parallel 

 to it is called a 

 diameter : any 

 line parallel to 

 the base mno is called a double ordinate. 



FARAB'OLIC. In geomttry, having the 

 form of a parabola. A parabolic asymptote 

 is a parabolic line continually approach- 

 ing to a curve, but never meeting it. A 

 parabolicpyramidoid is a solid figure which 

 was thus named by Dr. "Wallis. Parabolic 

 space, the area contained between the 

 curve of the parabola and a whole ordi- 

 nate. Parabolic spindle, a solid generated 

 by the rotation of a semi-parabola about 

 one of its ordinates. Parabolic spiral, 01 

 hMcoid, a curve arising from the suppo- 

 sition of the axis of the common parabola 

 bent into the periphery of a circle, the 

 ordinates being portions of the radii next 

 the circumference. 



PARAB'OLISM, (romparabola. In algebra, 

 the division of the terms of an equation 

 by any known quantity that is involved 

 or multiplied in the first term. 



PARAB'OLOID, from parabola, and ti(}&< , 

 like. A paraboliform figure : a solid 

 formed by the revolution of a parabola 

 about its axis. 



PARACE.N'TRIC, from sra^a, beyond, and 

 ZIVTQGV, the centre. Deviating from cir 

 cularity- By the paracentric motion of a 

 planet is meant the quantity which it 

 approaches nearer to, or recedes further 

 from, the sun or centre of attraction, in 

 its orbit: the difference by which the 

 real orbit of the planet diffeis from a cir- 

 cular orbit of equal area. 



PARACHROS'ISM, from *. beyond 

 and f<>K)j,time. An error in chronology. 

 by which an event is related as having 

 happened later than its true date. 



PABXCHU'TE, Fr. from tra^a, aziiinst, 

 and chute, a fall. An instrument om*- 



