s "logeum" ought to be not less than ten
feet nor more than twelve. Let the ascending flights of steps between
the wedges of seats, as far up as the first curved cross-aisle, be laid
out on lines directly opposite to the angles of the squares. Above the
cross-aisle, let other flights be laid out in the middle between the
first; and at the top, as often as there is a new cross-aisle, the
number of flights of steps is always increased to the same extent.

[Illustration: THE GREEK THEATRE ACCORDING TO VITRUVIUS]

CHAPTER VIII

ACOUSTICS OF THE SITE OF A THEATRE

1. All this having been settled with the greatest pains and skill, we
must see to it, with still greater care, that a site has been selected
where the voice has a gentle fall, and is not driven back with a recoil
so as to convey an indistinct meaning to the ear. There are some places
which from their very nature interfere with the course of the voice, as
for instance the dissonant, which are termed in Greek [Greek:
katechountes]; the circumsonant, which with them are named [Greek:
periechountes]; again the resonant, which are termed [Greek:
antechountes]; and the consonant, which they call [Greek: synechountes].
The dissonant are those places in which the first sound uttered that is
carried up high, strikes against solid bodies above, and, being driven
back, checks as it sinks to the bottom the rise of the succeeding sound.

2. The circumsonant are those in which the voice spreads all round, and
then is forced into the middle, where it dissolves, the case-endings are
not heard, and it dies away there in sounds of indistinct meaning. The
resonant are those in which it comes into contact with some solid
substance and recoils, thus producing an echo, and making the
terminations of cases sound double. The consonant are those in which it
is supported from below, increases as it goes up, and reaches the ears
in words which are distinct and clear in tone. Hence, if there has been
careful attention in the selection of the site, the effect of the voice
will, through this precaution, be perfectly suited to the purposes of a
theatre.

The drawings of the plans may be distinguished from each other by this
difference, that theatres designed from squares are meant to be used by
Greeks, while Roman theatres are designed from equilateral triangles.
Whoever is willing to follow these directions will be able to construct
perfectly correct theatres.

CHAPTER IX