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

202 THE OBNAMENTS, MOULDINGS, AND ENTABLATUBES.

The apparent modulus 22405" x4 = 8962" architrave ; - 8962" frieze; - 8962'/ cornice.

The given horizontal projection of)

the Entablature measured on the = 2*217 ft., ^^ = 0*088 ft. = horizontal modulus for the

25

line AB .

details of the Entablature.

The given apparent height of the cornice — 8962", -r-- = 373" = apparent modulus for the

details of the cornice.

The values of these two moduli being given, 0*088 feet for the projections, and 373" for
the apparent heights of the members of the cornice; then the details are figured in aliquot
parts, as shown in Fig. 1.

The apparent heights of the cornice = 4i + 5 + 4i. + 2 + 7 + l = 24 parts measured in seconds.

The horizontal projections of the

Entablature . . . . = 1 + 2 + 2 +11+ 2 + 2 + 5 = 25 horizontal aliquot parts.

Plate XV., Fig. 1.—The Entablature of the South Portico of the Erechtheium, seen from a

central point of view.

The Entablature of the South Portico of the Erechtheium is an example of a different
class of designs, the Portico being simply arranged in aliquot parts, without any corrections
being made in the 1st given heights, and the horizontal lines are executed as straight lines.
It is, therefore, the Entablature alone which is perspectively designed to suit a central point
of view, which is determined by the Lower Step being exactly embraced within the visual
angle of 45°. This fixes the point of sight at a distance of 372*8 inches from the line of
the architrave, and 135 inches below it. The whole given projection of the Entablature is
found to divide into 12 aliquot parts, and the whole apparent height into 36 apparent aliquot
parts. An inspection of Fig. 1, showing a section of the Entablature drawn to a scale of -6 of
the real size, will explain the details.

Plate XIV., Fig. 2 is a section through the cornice of the North Portico of the Erechtheium,
drawn to a scale of \ of the real size, showing the curve of the soffit to be i of an ellipse.

Plate XIV., Fig. 3. The detail of the architrave of the same Portico k of the real size.

There are no remains of colours externally on the Entablatures of the Erechtheium,
but on the ceilings, both of the North and of the South Porticoes, there are traces of the
engraved Ornaments, and also of the colours. In the ceiling of the North Portico the