DOI Page / Citation link:
https://doi.org/10.11588/diglit.4423#0203
154
'V
THE COLUMNS,
" Therefore, by the method of trial, by adding to the substance and reducing it, and
" by experiments in every possible way, they (the ancients) made them regular to the eye,
" and to appearance of good symmetry."
And we have seen that all the horizontal lines in the Parthenon were not corrected according
to any accurate optical laws, but were traced as the arcs of two circles only—the one for the
horizontal lines of the Porticoes, and the other for the return sides ; and I am not aware, even
with our present knowledge of optics, of any law by which we could accurately correct the
optical deceptions that are to be observed in a building like the Parthenon.
Vitruvius, when referring to the entasis, does not notice any concave appearance in the
shaft of the Column, but simply says—
" The method for giving the proper increase to the shaft towards the middle, which is
" termed entasis by the Greeks, so as to render it gradual and easily applicable, is explained
" by a figure at the end of the book."
In the case of the horizontal lines, we have seen that whatever the concave appearance
of the lines might have been, the outlines of the Steps and of the Entablatures are traced
as true mathematical curves, namely, as the arcs of circles ; and there is no example in Greek
Architecture of any curve being executed otherwise than as a conic section, and these curves
will, I believe, be found to have been employed in the outlines of the shafts of the Columns.
The outline is, I conceive, a true mathematical curve, traced so as to be agreeable to the eye,
and, if this be the case, accurate measurements will give the nature of the curve, and will
enable us to restore the original given elements, so as to recalculate the true outline of the
shaft of the Column in each example.
We may now proceed to give (1st) the observed facts, derived from careful measure-
ments, and (2nd) to suggest some general method for recalculating the entasis in each
example.
The following amounts of the entasis in the shafts of the Columns, measured from the
chord line, EP, to the arc of the curve, BA&5P, are taken from Mr. Penrose's measurements—
R
A
10
Parthenon . . 0
Propylsea . . 0
Jupiter Olympius . 0
&c.
•043
•035
11
&c.
•054 .
•0627 .
•118 .
&c.
•039 .
•0448 .
•066 .
&c.
0
0
0
&c.
Length of
shaft.
31-448 ft.
26-846 „
44-6 „
&c.
'V
THE COLUMNS,
" Therefore, by the method of trial, by adding to the substance and reducing it, and
" by experiments in every possible way, they (the ancients) made them regular to the eye,
" and to appearance of good symmetry."
And we have seen that all the horizontal lines in the Parthenon were not corrected according
to any accurate optical laws, but were traced as the arcs of two circles only—the one for the
horizontal lines of the Porticoes, and the other for the return sides ; and I am not aware, even
with our present knowledge of optics, of any law by which we could accurately correct the
optical deceptions that are to be observed in a building like the Parthenon.
Vitruvius, when referring to the entasis, does not notice any concave appearance in the
shaft of the Column, but simply says—
" The method for giving the proper increase to the shaft towards the middle, which is
" termed entasis by the Greeks, so as to render it gradual and easily applicable, is explained
" by a figure at the end of the book."
In the case of the horizontal lines, we have seen that whatever the concave appearance
of the lines might have been, the outlines of the Steps and of the Entablatures are traced
as true mathematical curves, namely, as the arcs of circles ; and there is no example in Greek
Architecture of any curve being executed otherwise than as a conic section, and these curves
will, I believe, be found to have been employed in the outlines of the shafts of the Columns.
The outline is, I conceive, a true mathematical curve, traced so as to be agreeable to the eye,
and, if this be the case, accurate measurements will give the nature of the curve, and will
enable us to restore the original given elements, so as to recalculate the true outline of the
shaft of the Column in each example.
We may now proceed to give (1st) the observed facts, derived from careful measure-
ments, and (2nd) to suggest some general method for recalculating the entasis in each
example.
The following amounts of the entasis in the shafts of the Columns, measured from the
chord line, EP, to the arc of the curve, BA&5P, are taken from Mr. Penrose's measurements—
R
A
10
Parthenon . . 0
Propylsea . . 0
Jupiter Olympius . 0
&c.
•043
•035
11
&c.
•054 .
•0627 .
•118 .
&c.
•039 .
•0448 .
•066 .
&c.
0
0
0
&c.
Length of
shaft.
31-448 ft.
26-846 „
44-6 „
&c.