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 CURVES OF THE HORIZONTAL LINES, 83

Chapter III.—The Calculation of the Horizontal Curved Lines.

1st. To determine by calculation the concave appearance of the several horizontal lines of a
Portico, when viewed from the point of sight 0, with the application of the calculation
to the lines of the East Porticoes of the Parthenon and of the Temple of Theseus, and
the determination of the rise of the curve of the Upper Step in the centre of each of
these Porticoes.

2nd. The forms of calculation required for tracing the line of the Upper Step as the arc of a
circle, both in the Portico and on the return side, also a few observations on the curva-
ture of the lines in the Inner Court of Medinet Haboo.

3rd. A few general concluding remarks on the proportions of the masses, and on the curvature
of the horizontal lines as now laid down; also on what remains to be done to complete
the general design, in the arrangement of the Columns and of the Entablatures,
with their proportions and appropriate curves and ornaments.