‹‹‹ Vitr. 1.1.8 | Table of Contents | Vitr. 1.1.10 ›››
9So the vessels called ἠχεῖα by the Greeks, which are placed in certain recesses under the seats of theatres, are fixed and arranged with a due regard to the laws of harmony and physics, their tones being fourths, fifths, and octaves; so that when the voice of the actor is in unison with the pitch of these instruments, its power is increased and mellowed by impinging thereon. He would, moreover, be at a loss in constructing hydraulic and other engines, if ignorant of music.
9In theatres, likewise, there are the bronze vessels (in Greek ἡχεια) which are placed in niches under the seats in accordance with the musical intervals on mathematical principles. These vessels are arranged with a view to musical concords or harmony, and apportioned in the compass of the fourth, the fifth, and the octave, and so on up to the double octave, in such a way that when the voice of an actor falls in unison with any of them its power is increased, and it reaches the ears of the audience with greater clearness and sweetness. Water organs, too, and the other instruments which resemble them cannot be made by one who is without the principles of music.