Pennethorne, John; Robinson, John [Ill.]: The geometry and optics of ancient architecture: illustrated by examples from Thebes, Athens, and Rome (London [u.a.], 1878)

Part II. Plate IV.

The Erechtheium No III . The NoktH ?°Htico trigonometiucaley corrected.

Fig. 1. The plan of the North Portico traced upon the Horizontal plane X Y and the position of the
point of sight 0 determined and the 1st. given proportions of the Portico traced upon the plane
X Z passing through the point of sight 0 .

35.154- length, of-upper step = 2.9Z& = modulus ofheiahts.

n

Steps________

. = 2

929 X

I ____

Co hut in

o

929 x t

' + i

Entothlccttcre _.

__ 2

929 x ;

y

Aerate•/-isv _ _

2

929



5 . 858

= .976

?«?. 54-2 leiigtJt of corona

2 . 929 X 72_____— 35 . H8 = w/icZe height.

== <f .4427 == height of pediment.

x_

net ■i'lciy.a,
corarux/

y..t .44Z7..

?>:">. 54-'l —s length/ of'6br-ona
32 . 202 == lenqfihj of frieze.

I

» 3

3 :" ;

..7 J

■3

C2

<k

8 58

Note. In this eocccmple the first given height of the
Column is shghtfy altered, /'rem the original/
proportions oend nuute —1<> 8-\-jr parts instead
of 9 parts, ttvus>
Entablature. = 2, Steps = 1, Column = ##parts.

.928.4--

* 3 2

'Wt.15u — length of upper step-

\0

7^;

X

X

/

/

^y

■4y

0b /

/

/

/

/

/

/

/

/<

/*!

s^

.'•15.154 = upper step______

<-

/

k—-"*«.-

.jo__..... 7y . i'l". = lower step-

——\+-\,

~^

' 'V

. /7.\.')«:{

()

|§|§||pp:; - ' WMMZMmmmmmr

^^^^^^^^^^^^^^

1U-. The plan of the Project ions at tire angle of the Portico nearest to
the point of sight O, traced upon the Horizontal plane X Y.

Fio. 3. The apparent Length and hreadth of the Middle step

o

MOM" + MOM = M = 150393 thin tjfiicaitity re(jii/a/r* the apparent
hei^lil from the lower step to the corona,. y



w



______________38.083 = middle step

— t—



V»

X

J'en it of sight 0

'£• T. The angle of the Portico nearest to the point of sight 0 fixed in position
and traced upon the plane II 0 7.. in this 1st. design the lineal magnitudes
are all commensurable, and the angular magnitudes calculated by the
log. tan. A— log. r + Log. a — log. b are slightly incommensurable.

Lorm

Fig. 5. The corrected design traced upon the Vertical plane HOZ, m this the
visual angles are all made commensurable, and the 1 rue executed
heights determined by the form Log.a=log.b + log. tan. A-10 will be

found to vary from the 1 st. given proportions by slight -additions and
diminutions.

'<vJ'o/{eJL:fy/l'^,^e''l/l:'/LnM-n . E. C.

■ fon.n/cJiola/ruxm/, dd>.