I 
PER 
PER 
ilie orifices of the lacteal veins, and tlie fee- 
ices are protruded towards the anus. 
PERITROCHIUM, in mechanics, de- 
•Jiotes a wheel, or circle, concentric with the 
base of a cylinder, and moveable together 
with it, about an axis. See Mechanics. 
PERIWINKLE. See Bcccinum. 
PERMIT, a licence or warrant for per- 
sons to pass with or sell good,s, having paid 
the duties of customs and excise. 
PERMUTATION of quantities, in alge- 
bra, the same with combination. See Com- 
iilNATION. 
PERORATION, in rhetoric, the epi- 
logue, or last part of an oration, wherein 
what the orator had insisted on through his 
whole discourse, is urged afresh with greater 
vehemence and passion. The peroration 
consists of two parts: 1. Recapitulation, 
wherein the substance of what was diffused 
throughout the whole speech is collected 
briefly, and cursorily, and summed up with 
new force and weigtit. 2- The moving the 
passions, which is so peculiar to the pero- 
ration, that the masters of the art call this 
part sedes affectuum. The passions to be 
raised are various, according to the various 
kinds of oration. In a panegyric, love, ad- 
miration, emulation, joy, &c. In an invec- 
tive, hatred, contempt, &c. In a delibera- 
tion, hope, confidence, or fear. The quali- 
ties required in the peroration are, that it 
be very vehement and passionate, and that 
it be short; because, as Cicero observes, 
tears soon dry up. 
PEROTIS, in botany, a genus of the 
Triandria Digynia class and order. Essen- 
tial character : calyx none ; corolla two- 
valved; valves equal, awned. There are 
two species, viz. P. latifolia, and P. poly- 
stachya, both natives of the East Indies. 
PERPENDICULAR, in geometry, a 
line falling directly on another line, so as to 
make equal angles on each side ; called also 
a normal line. See Geometry. 
Perpendicular to a parabola, is a right 
line cutting the parabola in the point in 
which any other right line touches it, and is 
also itself perpendicular to that tangent. 
Perpetual screw, is one which is acted 
upon by the teeth of a wheel, and which 
continues its action for an indefinite length 
of time, or as long as the teeth of the wheel 
exmtinue to act upon it. 
PERPETUITY, in the doctrine of an- 
nuities, is the number of years in which the 
simple interest of any principal sum will 
amount to the same as the principal itself ; 
or it is the number of years’ purchase to be 
given for an annuity which is to continue ■ 
for ever ; and it is found by dividing 1001, 
by the rate of interest agreed upon : thus 
allowing 5 per cent, the perpetuity is 
£ = 20; and at the rates usually adopt- 
ed, the perpetuity is as follows : 
33.333, &c. 
28.57, &c. 
25. 
22.22, &c. 
20 . 
16.66, &c. 
14.28, &c. 
12.5. 
These are the number of years purchase 
to be given for a perpetual annuity, on the 
supposition that it is receivable yearly. 
Perpetuity, in law, is where, if all that 
have interest join in the conveyance, yet 
they cannot bar or pass the estate ; for, if 
^by concurrence of all having interest, the 
estate may be barred, it is no perpetuity. 
PERRY, a drink made of pears, in the 
same manner as cyder is made from apples. 
See Cyder. The pears must be perfectly 
ripe, and to give the liquor a greater degree 
of tartness, some mix crabs' with them. 
The best fruit for making perry is such as 
is least fit for eating, as the choak-pear, 
boreland-pear, horse-pear, and the barber-, 
ry-pear. 
PERSEUS, in astronomy, a constella- 
tion of the northern hemisphere, which, ac- 
cording to the catalogues of Ptolemy and 
Tycho, contains twenty-nine stars ; but iiv 
the Britannic catalogue, stxfy-seven. 
PERSIAN wheel, an engine, or wheel, 
turned by a rivulet, or other stream of wa- 
ter, and fitted with open boxes at its cogs, 
to raise water for the overflowing of lands, 
or other purposes. It may be made of any 
size, according to the height the water is to 
be raised to, and the strength of the stream 
by which it is turned. This wheel is placed 
so, that its bottom only is immersed in the 
stream, wherein the open boxes at its cogs 
are all filled one after another with water, 
which is raised with them to the upper part 
of the wheel's circuit, and then naturally 
At 3 per 
, 100 
cent. i*- 3 - = 
100 _ 
'^2 
' 4 
100 _ 
■ 4 
4.1 ... 
100 
^2 
4.J 
100 _ 
0 
6 
100 _ 
6 
7 
II 
8 
100 _ 
.8 
