1000000031

E R

ClT

~cr.gne~

poinl<, from .he figure '0 the

b.fe,

and "ansf«

the leng,h of eaeh

perpendicuLtr,

{rain me place where

.touthes .he bafe, to the bale on ,he fitlc oppofi,e \0 .he poi nt

of diHance; fo -will the diamelrals drawn

the perpenJi–

cular! in the

hare, by

interCtétion with the diagonals. drawn

to the feveral trans(erred

d¡rhnces,

give the angles of

lhe

figures, and fa liDes drawn from

poinl tO

painr will

circllm–

feribe the fcenograph ie figure .

12.

io a I.ndnci p ,here

30y

Handing-waters, as

nvers,

ponds, and the like,

place the horiz6ntal li.e level wi.h the farthefl figh, or ap'

pearance of it. ' 3. If ,bere be any houre, or ,be like, io

the piélure, 'confider ,heir pofi,ion, th.t you may find from

what

POiOI

in lhe horizontal , lines to draw che

fronl

and

/ides ,herrof. 14. lo defcribi:,g ,biogs at • gre.t diflaoce,

obferve the proportiaD, both in magnitude and dillanee, iD

dr.ught, which .appears from the obje{l to the eye.

15.

ID colouriog and lhado\Viog of every thiog, you mutl do

the rame in

your pilture,

which you

obferve

with

your

e.ye,

efpeei.l\y in objeél. Iying ne.. ; but, according as the di–

llanee grows

grealer

and greater

lhe

co)ouu muO be

fain,er and fainter, ,in a' la(1 ,hey 10Ce ,be",lelve. in a dark–

ifu Iky-colour.

16.

Thé ca,optrics are bea feen in a com–

mon 100king-glaCs, or o,her polilhcd matter; where, ir the

P E R

PERSPECT[VE

CLAS. ,

in optiC!, differs from a tele–

feope in this: inllead of Ihe convex eye-glafs placed be–

hind ,be image,

make the rays of each pencil go pa–

..nd to ,he eye, there is placed a concave eye,glaf' a.

mueh before it ; whicA opens the conve¡ging ray', aod

mak.. them emerge parallel

the eye. See Op;,.,cs.

PERSP[RATl ON, io medicine, ,he evacuation of the jui–

ces of tbe body through ,he pores of ,he

n'¡n.

Perfpi–

ration is diainguilhed into fenfible a.d infenGble: and

here fenfible perfpiration i. the fame wi,h fweating, and

tnfenGble perfpiration ,hat which efcapes the . no,ice of

the f,nfes; and this laa is the idea affixcd to tbe w ord

perfpiration wheo ufed alone.

The malter of infenfible perfpi ration, i. a 'fine fubtl"

Ouid, which exhales from Ihe body

, he form of' a va–

pour, and proceeds from the \Vhole funace and from e–

,:ery cavity ; ir is of

OlD

aqueous and falioe nature, ¡nd

feems to have a great analogy with urine; becau(e

healthy Ila,e, the iocreafe of .he one diminifues ,he othor.

Many

experimenls

p,-.ove

its

exil1ence. Sanétorius found,

h aly, uoder

the

circumllances of a mOderate diet, mid·

dIe age, and eafy life, that ,he matter infenfibly perfpired

Was five-eigbts of that taken in for food; 'fo ,ha, there

ooly

remain~rl thH~:e·eights

fo r nutricion , and

fOf

the ex–

~crementS

the

nofe,

ears,

intefiines

bladder,

The

{ame author lhews, thél.l as much is evacuated

perfpi–

ra,ioo in olle day, as by flool in fourteendays.

BUt D r. Brpn Rohinfon, of Uublin, ha. found the

caCe very differeO! , bo.h in Englarld and

lrel.nd

, and

even in 50u.h CarollOa, io all which places he found ,hat

th.\! qu:&nti,y of

urille

cxcced~

rhat of pcrfpiration; and

th•• i! ,he meat and drink' of one day be four pounds aod

a hah, the ptrCpira,ion of ,h.. day \ViII be tWO pound.,

the urine 'IVO pounds five OBoces, aod Ibe fiool ,hree

eUDces.

glafs be exaMy O.t, the ohje{l i, ex. my lil<e i,.

ori~i

..l;

bu~,

if ,he

gl.Cs

be ¡fo,

/lat,

,he reeemblaoec ahe" from.,he

original; and .hat more odeCs , aceording as .he

gl.fs

dif–

"fers

from an

exatl:

plaoc.

J, .'ln

drawing catopuie

6g11r('~.J

the furface

,he glaCs is to be confidered, upon whieh yoo

mean' to have ,he ,e/le<!tion :

'Cor

whirh you

m~1l

m.ke

·"

particular íchnographical draught, or projetlion; whicn on

the glaf. mull 'ppear to be aplane full of

Iq~ares,

whieb

proje~lion

lransCer "hat Ihall be drawn

aplane, divided

in 'o the fame number ·of like Iquares ; where though the

draugh, may appear very confufed, ye, the reAeélion uf

on the glafs

will be 'very regular, ' proportion. I, .od regu–

larly compofed.·

18 .

The dioptric, or broken beam, may

be feen in • tube through a cryllal or glafs; which ha,l>-its

fu rface cut .into many o,hers, whereby ,he rayo of the ob–

jeél are broken. For to the eat of the Ofyllal, or wate.:,

the rays run flraight; but tben they break aod make In an–

gle, wbich alfo by lhe refraéled beams is made aod coo,i–

,inued on the o,her fide of the

f.me

/lat.

19.

Wheo ,befe

faces 00 a crytlal are returoed towards aplane placed di–

reélly beCore it, ,hey feparate themfelves at a goód difiance.

on the plane; beé:aufe they are all

~ireéled

to various

diflant places of the fame, .S.. OPTICS ,

P E S

T he matter of f\Veat is feparated from the

blood

the miliary glands, and is tberefore much more grof.

thao thar of infcafible pcrfpiration; for as there are

glands which ferve for the excretion of thi. lan Ouid,

i. fuppofed tO procced

fr.om

,he extremities of tbe capil–

Jaryarteries.

The ufe of perfpira,ioois to preferve the fuppleoefs of

th. papilla: of the Ikin; to c.rry the faline p.rticles off

from ,he

blood,

aod by ,bis meansto rende,;t more pure;

to preferve the body from

variaus

difcafcs;

and

to contric–

bute to the cure of ,he moa dangFous diaempers. lt

may be promoted by exercife, by dry friélion. wi,h a

coarfe linen·cloth or a Oelh·brulh, by warm baths, aDd

walhing .he

h.nd

., ftet, head,

&c.

PERTH. ,he capital of the couoty of the fame Dame

Scodand, thirty miles Dorth of Edinburgh .

P ERTHAMBOY, a ,porr-,own of New'Jerfey, in Nortb

America: W.long.

74°.

N . lat;

40° 45'·

PERTINENT OF LA'NDS, iD Seots law. S.. LAW, Tit_

xiii.

18.

PERU, formerly a powerful empire iD South Ameriea, but

now a

province of

Spain,

fituated bctween

60°

and

of ",ell longitude, and be,w«n the equator and

2S"

Couth lati,ude, being near

2000

mile. in leng'h from

north to fouth,

and

from:2oo to

;00

broad : ir is bound:–

.d by Popayan, on the north; by ,he moun,ains of AD–

des, on ,he eafl ; by Chili and La Pla,a, on the [outh ;

and by the Pacific Ocean, on the wefl.

PERUGIA, a ci,y of Italy, in ,be tetritories ofthe pope:

E. long.

13° 16',

N . I.t.

43°.

PERUV IAN

BARK .

Sce

C'~~HONA.

PESARO, a ci.y or Italv, in the p,oyince of Urbino, fitu.

ated

on the gulph o( V enice! E. long.

14°,

N . Iat.

H~'

PES.SAR

in medicine, a folid fubltance 'co",pofed of

wool; lin', or IiDen, mixed with powdet, oi\s, wa",

6"..

IlUde