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

THE FIRST GIVEN PROPORTIONS.

25

The whole amount of the Projection, from the face of the frieze to the edge of the
Lower Step, is always regulated by the modulus that governs the heights, and the whole
amount of the Projection is then divided into a given number of aliquot parts ; one of these
parts is made a fresh modulus, and all the Projections become multiples of this given
quantity.

In the Doric Porticoes, the modulus regulating the vertical heights is % of the whole
height, and, in every example of the Doric order, we find all the Projections to be regulated
by some lesser multiple of this given modulus.

In the Ionic Porticoes of the Erechtheium, the modulus regulating the vertical heights
is _^ 0f the whole height, and the Projection of the Steps is equal to this modulus; but the
whole amount of the Projection, from the face of the frieze to the edge of the Lower Step,
is made equal to | of the whole height, the same as in the Doric, thus-

Given

height in
feet.

50-668
9

43-227

Total Projection

taken from the frieze

to the Lower Step.

= 5-6298 ft.

5-6298

9

28-856
9

28-674
9

35-15
9

28-1307
9

4-803 ft.
3-199 ft.
3-186 ft.
3-905 ft.
3-125 ft.

17

4-803
15

3-199
15

3.186
24

3-905
24

3-125
50

Modulus
regula-
ting the
Projec-
tions. „

= -331 ft.

= •32
= •213
= •132
= •1627
= -0625

These
moduli
will he
found to
regulate

all the
) Projec-
tions in

the
selected

Athe-
nian ex-
amples.

Fig. 1. The Parthenon......

Fig. 2. The Propylaea, centre Portico .

Fig. 3. The Propylsea, north wing . .

Fig. 4. The Erechtheium, east Portico .

Fig. 5. The Erechtheium, north Portico

Fig. 6. The Temple of Theseus . . .

Fig. 7. A Summary of the arrangements of the Projections of the several Porticoes.

Why the whole given Projection in the Parthenon should be divided into 17 parts,
in the Propyhea into 15 parts, and in the Erechtheium into 24 parts, we can at present assign
no special reason, and simply give the numbers as observed facts, but the modulus being given
for any example, then all the minor Projections of the Architrave, Cornice, et cetera, are
regulated by the given modulus.

THE FIRST INCLINATION INWARDS OF THE MASSES OF THE COLUMNS

AND ENTABLATURES.

In all the works of Egyptian Architecture we find the walls have a considerable incli-
nation inwards, the Columns and Obelisks likewise dimmish gradually from the lower to the