An Epitome of Book III of Vitruvius Written by David Trumbull
Following the introduction addressed to the Emperor Octavian Caesar, Vitruvius,
in Chapter One,
writes of symmetry as manifest in the human body and as applied to the design of temples.
By symmetry he means each element of the structure having the correct proportion to other
elements and to the whole, as is the case with the human body. He maintains that nature has
so designed the body that the proportions, taken together, result in a pleasing form.
He notes how celebrated artists, in rendering the body, have produced works
of renown by observing and
copying the proportions that nature provided. Similarly, then, he concludes, a building is
harmonious if it follow this same principle of proportion as that manifested in the body.
Vitruvius cites as his authority the ancient Greek architects. Those
master builders derived the proportions for buildings from the art and science
displayed by nature in composing the human body. They copied those proportions
to good effect and passed them down as the canon for architects.
Indeed, all the axioms of architecture can be traced to the human body.
For example, ten being the number of fingers, is a perfect number,
very serviceable in the science of architecture. The exultation of ten
also owes to the theories of the pre-Socratic philosopher Pythagoras who
placed mystical meaning on numbers. According to Pythagoras ten was
perfect because it is the sum of the first four whole numbers, which themselves
were auspicious as they express the relations between the chief musical intervals.
The octave is a two to one ratio. The fifth, three to two. The musical fourth is four
to three. On the contrary, some argue that six is the perfect number.
This is because six
is the sum of one, two, and three which also express the corresponding fractions
of the whole: one is one-sixth of the whole, two is one-third, and three is one-half.
Later, by this same reconning, Saint Augustine also declared six the perfect number.
Six has a further claim as the perfect number, being the height of a man as expressed
in feet. Later we shall see how Vitruvius derives the proper width to height ratio
for building columns from this observation of the human body.
By adding these two perfect numbers six and ten Vitruvius arrives at 16, the
most perfect number. From the observation that the foot, from which is
derived the height of a man, is sixteen finger-breadths in length, Vitruvius
concludes that the finger is the basic unit, or modulus, for the proportions
of the body. This same principle of design based on a modulus he applies to architecture.
In Chapter Two Vitruvius writes of the seven classifications of temples based on the
placement and number of rows of columns relative to the cella, the
room in which is housed the statue of the god. The classifications, in order of
complexity are: in antis,
prostyle, ahphiprostyle, peripteral, pseudodipteral,
dipteral, and hypaethral. Along with the description of each classification
Vitruvius cites at least one example of an actual temple in of that classification.
In Chapter Three Virtrivius continues the analysis of the plans
of temples, examining five classes of temples according to the placement
of the columns relative each to the other. The pycnostyle with columns close
together and the systyle with the intercolumniations a little wider are
both dismissed as incommodious. On the other hand the diastyle with rather wide
placement of columns and the araeostyle with too wide a gap between the supports
are condemned for the squat appearance they present and for the insufficient support
they provide for the upper members. Vitruvius, like Goldilocks, choses a happy
mean between these two extremes and calls it the eustyle, or "well columned."
This arrangement, with the space of three columns between the two central columns affords
unobstructed view of the statue of the god and ample space for worshippers to pass through
to the temple door. The remaining columns are placed as a distance of two-and-quarter column
widths apart for a result that satisfies the Vitruvian canon of firmitas, utilitas,
and venustas --strength, utility, and beauty.
He then proceeds to set forth the principles for establishing the proportions for the
elevation of the temple. He lays down rules for determining the height of columns and
the ratio of the thickness to the height. He concludes with discussion of the tappering
of the column from bottom to top and the entasis or slight swelling
at the middle of the column which produces a pleasing appearance.
In Chapter Four Vitruvius discusses the laying of the foundation and base of the
temple. He prefers that temples be built on solid ground, like the skyscrappers of
New York City built on the bedrock of Manhattan Island. Lacking that, he describes
the process of driving wooden piles in loose or marshy soil to create a firm base for
laying the foundation stones. The technology of Vitruvius is indentical to that
employed in the Bay Back district and other neighborhoods
of Boston build on "made-land" filled in over marshes, swamps, and estuaries.
Vitruvius would have the steps to temple always be an odd number so that the first
step up and the final step onto the base be made with the right foot. As for the base itself,
Vitruvius directs the builder to make it slightly convex for if it were perfectly flat
it would appear to be concave. This is a subtle adjustment, such as the entasis of the
column, which may be observed in the Parthenon on Athen's Acropolis and others of the
finest buildings of antiquity.
In Chapter Five Vitruvius sets forth the specifications for the Ionic Order.
He describes the bases, shafts, capitals, and the entablature and gives the proportions
for each element. He specifies that the corner and side columns are to be set
so that their inner sides, which face toward the cella wall, are perpendicular,
but their outer sides tapper from bottom to top. He give especially attention
to adjustments to the proportions in capitals and upper elements in the case of
very tall structures, for, as he writes, "the higher that the eye has to
climb...it fails when the height is great, its strength is sucked out of it,
and it conveys to the mind only a confused estimate of the dimensions.
Hence there must always be a corresponding increase in the symmetrical proportions
of the members."
Having prescribed a code for general strength and safety in building
and giving all the rules for proportion and symmetry as applied to the Ionic Order,
Vitruvious concludes Book III with instructions for directing rain-water from
the roof out of the path of persons passing through or by the temple. He will treat of
the Doric and Corinthian Orders in Book III.
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Here begins Vitruvius' Book III on architecture, being the
continuation from Book II.