PLA 
from tlie number of its angles, as a penta- 
gon, hexagon, &c. '3. Irregular place, is one 
whose sides and angles are unequal. 4. 
Place of arms, is a strong city or town 
pitclied upon for the chief magazine of an 
army ; or, in a city or garrison, it is a large 
open spot of ground, usually near the centre 
of the place where the grand guard is com- 
monly kept, and the garrison holds its 
rendezvous at reviews ; and in cases of 
alarm to receive orders from the governor. 
6. Place of arms of an attack, in a siege, is a 
spacious place covered from the enemy by a 
parapet or epaulement, where the soldiers 
are posted ready to sustain those at work 
in the trenches against the soldiers of the' 
garrison. 6. Place of arms particular, in a 
garrison, a place near every bastion where 
the soldiers sent from the grand place to the 
quarters assigned them, relieve those that 
are either upon the guard or in sight. 7. 
Place of arms without, is a place allowed 
to the covert way for the planting of cannon, 
to oblige those, who advance in their ap- 
proaches to retire. 8. Place of arms in a 
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 com- 
pany, to assemble in. 
PLACENTA. See Midwifery. 
PLAGIANTHUS, in botany, a genus of 
the Monadelphia Dodecandria class and 
order. Essential character : calyx five- 
cleft ; petals five, two approximating, re- 
mote from the other three ; berry. There 
is but one species, viz. P. divaricatus, a na- 
tive 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 regulations 
by our statute law for the performance of 
quarantine in order to prevent the extend- 
ing of infection. 
PLAIN fable, in surveying, a very simple 
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 by a ful- 
crum, 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 pa- 
per, are divided into equal parts every 
way. It has also a box with a magnetical 
PLA 
needle, and a large index with two sights ; 
and, lastly, on the edge of the frame, are 
marked degrees and minutes. See Sur- 
veying. 
Plain number, is a number that may be 
produced by the multiplication of two num- 
bers into one another : thus 20 is a plain 
number produced by the multiplication of 
5 and 4. 
Plain problem, in mathematics, is such 
a problem as cannot be solved geometri- 
cally, but by the intersection eitlier 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 only have two 
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 metal from the 
shield. This has been sometimes used as a 
mark of bastardy, and called champaigne j 
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. See Pleuronectes. 
PLAN, in general denotes the represen- 
tation of something drawn on a plane : 
such are maps, charts, ichnographies, &c. 
See Map, Chart, &c. 
The term plan, however, is particularly 
used for a draught of a building, such as it 
appears, or is intended to appear, on the 
ground ; shewing the extent, division, and 
distribution of its area, or ground- plot, into 
apartments, rooms, passages, &c. A geo- 
metrical plan is that, wherein the solid and 
vacant parts are represented in their natu- 
ral proportions. The raised plan of a build- 
ing, is the same with what is otherwise 
called an elevation, or orthography. A 
perspective plan, is that exhibited by de- 
gradations, or diminutions, according to the 
rules of perspective. 
PLANARIA, in natural history, a genus 
of the Vermes Intestina class and order. 
Generic character ; body gelatinous, flat- 
fish, with a double ventral pore ; month 
terminal. There are about fifty species di- 
vided into six sections, distinguished by the 
number of their eyes ; A without eyes : B 
