uld be placed, may be described as follows. If the theatre
be of no great size, mark out a horizontal range halfway up, and in it
construct thirteen arched niches with twelve equal spaces between them,
so that of the above mentioned "echea" those which give the note nete
hyperbolaeon may be placed first on each side, in the niches which are
at the extreme ends; next to the ends and a fourth below in pitch, the
note nete diezeugmenon; third, paramese, a fourth below; fourth, nete
synhemmenon; fifth, mese, a fourth below; sixth, hypate meson, a fourth
below; and in the middle and another fourth below, one vessel giving the
note hypate hypaton.

3. On this principle of arrangement, the voice, uttered from the stage
as from a centre, and spreading and striking against the cavities of the
different vessels, as it comes in contact with them, will be increased
in clearness of sound, and will wake an harmonious note in unison with
itself.

But if the theatre be rather large, let its height be divided into four
parts, so that three horizontal ranges of niches may be marked out and
constructed: one for the enharmonic, another for the chromatic, and the
third for the diatonic system. Beginning with the bottom range, let the
arrangement be as described above in the case of a smaller theatre, but
on the enharmonic system.

[Illustration]

4. In the middle range, place first at the extreme ends the vessels
which give the note of the chromatic hyperbolaeon; next to them, those
which give the chromatic diezeugmenon, a fourth below; third, the
chromatic synhemmenon; fourth, the chromatic meson, a fourth below;
fifth, the chromatic hypaton, a fourth below; sixth, the paramese, for
this is both the concord of the fifth to the chromatic hyperbolaeon, and
the concord[8] of the chromatic synhemmenon.

[Note 8: Codd. _diatessaron_, which is impossible, paramese being
the concord of the fourth to the chromatic meson, and identical with the
chromatic synhemmenon.]

5. No vessel is to be placed in the middle, for the reason that there is
no other note in the chromatic system that forms a natural concord of
sound.

In the highest division and range of niches, place at the extreme ends
vessels fashioned so as to give the note of the diatonic hyperbolaeon;
next, the diatonic diezeugmenon, a fourth below; third, the diatonic
synhemmenon; fourth, the diatonic meson, a fourth below; fifth, the
diatonic hypaton, a fourth below; sixth, the pros