Gabb, Thomas: Finis pyramidis or Disquisitions concerning the antiquity and scientific end of the great pyramid of Giza, or ancient Memphis, in Egypt, and of the first standard of linear measure (Retford, 1806)

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euch unnatural attitudes in their statues, or any such
fallacious changes of symmetries, to consult optical ef-
fects. The columns of the Parthenon, which Mr. Stu-
art makes nearly 40 feet high, have the upper diameter
47 minutes, which is a greater contraction, than Vitru-
vius allows for columns of 15 feet high ; and by his rule
of optics, the top diameter would he 52 minutes instead
of 47. A good rule would be to contract the diameter
at the upper part of shafts, to 50 minutes in all heights
whatever, and our eyes will assuredly perceive the pro-
priety of it.

But I now come to the consideration of increasing the
delicacy of shafts of internal columns, and that too,more
or less, in proportion as they are further removed from
the full influence of the external light, Hence Vitru-
vius judiciously attended to their internal situations in
settling the ratio of the degree of slenderness they are
to have, when standing just within external colnmns,
as in the pronaos of a Temple ; and when standing at
nearly twice that distance from external columns, as in
the middle of the ancient Stoai, wherein the Stoic phi-
losophers walked when they delivered their precepts; or
in porticoes behind theatres ; in which the row of co-
lumns along the middle, was distant from the external
columns, and from the wall, the length of a column.
The rule for reducing the shaft, in the pronaos of a
Temple, is, if the external columns are 8 diameters high,
the internal shall be reduced till their diameter will re-
peat 9 times in the same absolute height. If the exter-
nal are 9 diameters high, the internal shall be reduced
in the same ratio, viz, as 8 was to 9, so 9 will be to 10
diameters and 7| minutes : again if the external are 10
diameters, the ratio will be for the internal, as 9 diame-
ters