602 
P L A 
P L A 
required length, where it muft be fixed by ftrong fcrews, 
the axis being turned by manual exertion, by horfes, 
(team, water, or any other power, and having its motion 
regulated by a fly-wheel. The planes are loaded, to keep 
them in contaft with their work, by a long beam of wood, 
fet up on end upon the fides of the box, and conne&ed 
therewith by being divided into two cheeks, which at the 
lower fides are formed to an arc of a circle, and united to 
the box by chains, in the fame manner as the beams of 
fteam-engine3 are connefled with their pifton-rods. The 
upper part of the beam is made to pafs always through 
one point by Hiding between friflion-wheels, or otherwife 
in a tube hung on two pivots perpendicularly over the 
centre of the work, and at fuch heights as may be moll 
convenient for the length of the ftroke required : the 
connefting-rod from the crank before mentioned is 
jointed to the upright beam, near its lower end, and by 
this means the motion is given to the box of planes, the 
chains and arches at the bottom allowing it in all pofitions 
to preferve the plane horizontal. To guide the box of 
planes in a reftilinear motion, and alfo to bear them off 
when they have been reduced to the depth required, 
fences are ufed, which are irons Aiding perpendicularly in 
tubes or fockets in the box or frame, and clipping a 
tongue, or ruler, fixed in the direction of the required 
ftroke, in the frame fupporting the bench. 
PLANIPET'ALOUS, adj. [ planus , Lat. flat, and vrs- 
taXov, Gr. a leaf.] Flat-leaved, as when the fmall flowers 
are hollow only at the bottom, but flat upwards; as in 
dandelion and fuccory. 
To PLAN'ISH, v. a. [from plane. Topolifh; to fmooth. 
A word ufed by manufacturers. 
PLAN'ISPHERE, / A fphere projected on a plane ; a 
map of one or both hemifpheres.—There be two manners 
cf this defcription [of the globe] according to art; the 
firft by parallelogram, the other by planifphere. Gregory's 
Pojlhum. 1640. 
Planisphere is fometimes alfo confidered as an aftro- 
nomical inftrument, ufed in obferving the motions of the 
heavenly bodies; confifting of a projection of the celeltial 
fphere upon a plane, representing the ftars, conftellations, 
&c. in their proper fituations, diftances, See. Such is the 
ajlrolabe, which is a common name for all fuch projec¬ 
tions. 
Among the infinite number of planifpheres which the 
different planes of projection, and the different pofitions 
of the eye, would furnifh, there are two or three that have 
been preferred to the reft. Such are that of Ptolemy, 
where the plane of projection is parallel to the equator; 
that of Gemma Frifius, where the plane of projection is 
the colure, or folftitial meridian, and the eye the pole of 
the meridian ; that of John de Royas, a Spaniard, whole 
plane of projection is a meridian, and the eye placed in 
the axis of that meridian at an infinite diftance. 
The common defeCt of all thefe projections is, that they 
diftort and alter the figure of the conftellations, fo that 
it is not eafy to compare them with the heavens ; and that 
the degrees in fome places are fo fmall, that they afford 
no room for operation. Thefe faults M. de la Hire en¬ 
deavoured to provide againft in a new projection, or pla- 
nifphere ; where it is propofed the eye fhall be fo placed, 
as that the divifions of the circles projected (hall be fenfi- 
bly equal in every part of the inftrument. 
PLAN'ITY, /. Plainnefs, clearnefs. Bailey. 
PLAN'ITZ, a town of Saxony, in the circle of Erzge- 
birg: three miles fouth of Zwickau. 
PLANK, / [planche, Fr.] A thick ftrong board.— 
They gazed on their (hips, feeing them fo great, and con- 
fifting of divers planks. Abbot’s Defer, of the World .— 
Some Turkifli bows are of that ftrength, as to pierce a 
plank of fix inches. Wilkins. 
The doors of plank were ; their clofe exqtiifite, 
Kept with a double key. Chapman's OdyJJey. 
Deep in their hulls our deadly bullets light, 
And through the yielding planks a paffage find. Dryden. 
Be warn’d to fhun the watry way, 
For late I faw adrift disjointed planks, 
And empty tombs ereCted on the banks. Dryden. 
Plank, in commerce, is a general name for all timber 
(excepting fir) which is from one inch and a half to four 
inches thick: if of lefs dimenfions, it is called board. 
Thus we fay, oak -plank. 
To PLANK, v. a. To cover or lay with planks.— If 
you do but plank the ground over, it will breed faltpetre. 
Bacon's Nat. Hijl. 
A (feed of monftrous height appear’d, 
The fides were plank'd with pine. Dryden. 
PLANK'ENBERG, a town of Auftria : four miles 
fouth-fouth-weft of Tulin. 
PLANK'ENSTEIN, a town of the duchy of Stiria: 
four miles fouth of Windifch Weiftritz. 
PLANK'ENWARD, a town of the duchy of Stiria: 
eight miles weft of Gratz. 
PLANK'ING, /. Covering the timbers of a (hip with 
plank; fometimes quaintly called fanning. 
PLAN'NER,/. One who forms any pian or defign. 
PLAN'NING, /. The aCt of forming a plan. 
PLA'NO-CON'C AVE, adj. Plain on one fide and con¬ 
cave on the other. 
PLA'NO-CON'C AVE, f. A lens plain on one fide and 
concave on the other. 
PLA'NO-CO'NICAL, adj. Level on one fide and co¬ 
nical on others.—Some few are piano-conical , whole fu- 
perficies is in part level between both ends. Grew. 
PLA'NO-CON'VEX, f. Flat on the one fide and con¬ 
vex on the other.—It took two objeft-glades, the one a 
plano-convex for a fourteen-feet telefcope, and the other 
a large double convex for one of about fifty feet. Newton's 
Optics. 
PLA'NO-CON'VEX,/. A lens plain on one fide, and 
convex on the other. 
PLAN'SCH WITZ, a town of Saxony, in the Vogtland: 
three miles weft of Oelfnitz. 
PLANT,/ [Saxon.] Any thing produced from feed ; 
any vegetable production.—Some plants the fun-lhine alk, 
and fome the (hade. Harte. —It continues to be the fame 
plant , as long as it partakes of the fame life, though that 
life be communicated to new particles of matter vitally 
united to the living plant, in a like continued organiza¬ 
tion, conformable to that fort of plants. Locke. 
Once I was (kill’d in every herb that grew. 
And every plant that drinks the morning dew. Pope. 
Plants compofe the fecond of the three kingdoms of 
nature. To define the limits of thefe, the animal, the 
vegetable, and the foflil, kingdoms, has exercifed the in¬ 
genuity of philofophers : when foflils were believed to 
poffefs a vegetative power, which even Tournefort main¬ 
tained, the chief difficulty lay in diftinguifliing them 
from plants; but, fince the mineral kingdom has been 
afeertained to depend on the laws of chemiftry alone, all 
ambiguity on that fide of the queftion is removed. On 
the other hand, in proportion as the phyfiology of plants 
has been ftudied, theiranatomy, nutrition,developement, 
and propagat ion, have been found fo nearly allied to fimi- 
lar functions in animal bodies, that increale of knowledge 
has but augmented our perplexity. The following are 
among the mod approved definitions, intended to diferi- 
minate between animals, vegetables, and foffils. 
1. Jungius, in his Ifagoge, p. 1, fays, “A plant is a 
living body deftitute of fenlation ; or it is a body attached 
to fome certain place or feat, whence it derives powers of 
nourifttment, increafe, and propagation.” Linnteus cites 
this paffage inaccurately in Phil. Bot. 1. He obferves, 
in a manufeript note, that the floating fea-weeds and Con- 
fervte form an exception. 
2. Boerhaave confiders a plant as “ an organic body, 
attached by fome part of itfelf to fome other body, whence 
it derives nourifliment.” 
3. Ludwig aflerts, that “ Natural bodies conftantly en¬ 
dowed 
