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472

P E R S P E

BC: from whic!' you ha.. a (root view o( the whole body

..f ,he chureh, whh all \he pillars,

<be.

eaeh fide: ,heo

/ix your oorizoo a, any height you ,hink proper, as at DE:

bi[<él i, by the perpendicular EA; anJ where thefe ,wo

lines inferfcél, i, the poin, of fight F. This perpendicu–

lar will p.lfs ,hrough ,he centre. of all ,he arche, in the

dome or cupol. : ",hich centres may be fouod by aoy three

given poinu. Next divide

yaur

bare line ioto any given

lIumber of feel ; aod the vifual lioe., ruled from thefe di–

vifi ons

,be poini of figh" will reduce all your objeéls to

their jufl proportion, by feuing off ,heir heigll, upon a per–

pendieul.r ,.ifed at ,heir refpeélive diflanees. The bafe,

jn the example here givco, is divided ¡nto twelve equal parts

of¡jye feet eaeh ; from wbich (fuppofing your fronl eolumn

to be 3S fee, high) take feven divifioos from ,hebaCe line of

your drawing, and fet them off upon tbe perpendicular G H

then (fuppofin& this eolumn to be five (eet thick at the bafé)

(e, off one of tbofe divifions upon ,he parallelIK, whieh i.

.be breadth required . So tha" by proportiooiog ,his fcale

to any

(li(l~ne~

by ·the 'foregoing direélioo., you may not

ooly find ,be dimeDfion, of all your columo!, but alfo of e-

1'''y d,fiinél pa" of ,hem, as well as of all ,he doo", .wiD–

dow., ang o,ber objeél, ,ba, occur. For inflance: Having

found the heigbt and breadth of your 6rCl or oeareCl colunlO

G, draw (rom the ,op and bOllom of ,he faid column

tbe point of figh! the Jines HF and KF ¡ after which,

r~le

t he lindF from the bafe of the column to the point of úght,

and you have the heigh.t and

~readth

of all the ,ell of the co–

lumo" as ha, beeo already fhewn in fig . 3.

By ruling liDe, from the poiots

a,h,e,d,

Sec. to the poiot

of fight, you will fee that all the fummi.. aod baf.. of

Jourcolumns, doors, windows,

&c.

mull: tend

immediat~.

that poiot ¡ and by lin", drawo from Ihe poiou t ,2,3,

,.,

&c.

eaeh fide, to Ihe correfpondeot poinu on ,he op–

pofite fide, may be feeo all Ihe pans of your buildiog lying

upon the fame·.parallel:

7 0 dra'W an ohlique

"i,'W. See 6g. 6. of Plate CXLIV.

FirCl draw YOUt horizontalline AH ¡ then, if your favou_

,jle objeél be on ,he right hand, a, at C, place yóurfelf OL

the le(t hand upoo the bafe line,. as

D ¡ then from that Cla–

tioo ereél a perpendicular DE, whicb wil! pafs tbrough ,be

"orizon at ,he point o( fighl F; to which rule tbe diagonals

GF and HF, which will fhew the roof and bafe of your

priocipal building

and wil! alfo, as be(ore direéled, ferve

a, a CI.ndard for oall the rell.·

Obferve alfo, ehh., in direél or oblique views, whether

tbe profpefl ·before you make a curve

for if it does, you

lIluCl be careful to make the fame cur.e in your dra\Ving.

tlraw

pufttllive

ví~.

rw/urein

are accidental

p,inll.

See fig. 7 . of. Plate CXLIV.

Rule your horizontal line

.h,

.nd on one part of it fix

)'our point of fight, as at

from which rule the diagonal,

and

on the one fide, .nd

and

( q

on ,he o,her

which

will fhew ,h. roof, and bafe, of all ,he houfes in tbe tlreet

d ircélly facing you; (fuppofing yourfdf ploccd a; A in the

cen,!e of the bafe line:) Theo fix your accidental points

.nd

upon the horizontal line, and rule (rom thcm to the

angles i'¡'nd

1m,

(where the Clree"

one.ch

fide take a dif–

(erent direéliun, ,oward, tbe accidental points

and

the lines

and

give ,he roo(s and bafe, of all the build–

ing' OD ODe

Gde,

aad

do on t he other.

A cciderrtal poio.. feldo", inter,ene where the dinance

¡.

fmall, as in noblemens feats, groves, canals,

6,.

which

may be drawn by ,be Cldél rule, of perfpeélive: bUI where

(he profpeét is extenfive and varied, including mountains,

bridges, ce.aHles, rivers, precipices, woods,

Cil;¿S,

ec.

will require (uch an in60lte number of accidental poinls,

that it will be bener 'o do ,hem as Dature fhall diélate, aDd

your

~ipeoed

judgment approve.

7 0jindlh. (mlre/or Ihe r.%/ahoufe, inan ohliquevie'W,

See fig. 8. ofPlate CXLlV.

Suppofe from the point of figbt A, the vifual Jine, AB

and AC'be drawn, BC bcing one perpendicular given, and

DE the o,her, rule tbe

diago~als

from O t0

aod fróm

E tO E, and Ihe perpendicular FG, raifed ,hroygh the

point of their interftélion, will fhew (he true centre of (he

roof,

will appear by ruling the lil c, GE and OC.

For want ofbeingacquainted with this neceLTary rule, maoy

who have been well verfed in otber 'pa", of perfpetli.e, havo

fpoiled thc 1001<

',heir piélure, by drawing the roo(s of

,heir houfes out of ,heir irue perpendicular.

Ihall con elude by giving a few praélical' rules.

Let every line, 'which in the objeél,. or geometrical figure,

i, Clraight, perpeodicular, or parallel 'o jts bafe, be fo

alf~

fcenographic delineation.

!2.

L~t

the

liDes,

which

in the objeél return at right angles from the fOfe-right fid.,

be drawn fcenographically from the vifual poiot. 3. L et

all f1raight lines, \Vhici> in ,he objeél r<turó (rom the fore–

right fide, rUO in a fcenographic figure into the horizoo,a1

lioe. 4. Let the objeél you intend to delineate, Clandiog

your right-hand, be placed alfo on the right.hand of th.

viCual point ¡ and tha, on the left-haod, on tbe lef,-hand of

the fame point; .nd that which is juCl before, io the mid–

die o( il. 5. Let ,bofe ' lines which are (io tbe objeél) e–

quidiClant to ,he re,urning Jine be drawn io the fceoogra–

phic figure, from Ihat poiot found in the horizon. 6.

feuing off the altitude of columns,

ped~Clals,

anel-

,~e

like,

meaf.re

the height from ,he bafe line upwards,

the fron'

or fore.right fide; and a vifual ray dOWD that poiot in th.

froo, fhall limit ,he altitude of the column or pillar, all th",

way behind the fore-rigbt fide, or orthographic

appear~oce.

eyen to the vifual poiot. Tbis 'rule you mul! obfer.,e ,n all

figures, as well where there is a (rooí

or'fore-righ~

C.de

as where there is

Done.

7. lo delineating

oval5,

clrclcs.

arches, erolTes, fpirals, and crofs.arches, or :lny other

fi·

gure in the roof o( any room, 6rCl dra", ichnographicaHy,

and fo with perpendiculars from tite moCl.eminent pOlOU

thereof, carry i, up un,o the cieliog; from which fcveral

poiols, carry on

the

figure.

The

cen'tre in any

fceno~

graphic regular figure is (ound by drawiog lines from oppo–

Ii,e angles: for ,he point \Vhere the diagonal, crofs, i,

th~

centre. 9. A ground-plane of fquares is

alik~,

both abov.

and below the horizontal line ¡ ooly the more it i, dillanl

above or beoeach the horizon, ,he fquare,

will

be fo mueh

the largcr or \Vider,

10.

In drawiog a perfpeélive figure,

where many lines

com~

togethcr, yau may, for the diretl·

ing of your eye, draw ,he diagonal. in <cd

the .ifual I1ne.

in black; the perpendiculars)n greco, or other different ca·

lour, from that which you intend the figure fhall

of,

1 1:

H aving confirlered the heigbt, diClance, and

pofillo~

the figure, and drawn it accordiogly, \Vitl> fide or angle a·

gaiaIl the bare

raife perpeDdícuJars from tbe fever.1 angle.,