eia]) 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.

10. The architect should also have a knowledge of the study of medicine
on account of the questions of climates (in Greek [Greek: klimata]),
air, the healthiness and unhealthiness of sites, and the use of
different waters. For without these considerations, the healthiness of a
dwelling cannot be assured. And as for principles of law, he should know
those which are necessary in the case of buildings having party walls,
with regard to water dripping from the eaves, and also the laws about
drains, windows, and water supply. And other things of this sort should
be known to architects, so that, before they begin upon buildings, they
may be careful not to leave disputed points for the householders to
settle after the works are finished, and so that in drawing up contracts
the interests of both employer and contractor may be wisely
safe-guarded. For if a contract is skilfully drawn, each may obtain a
release from the other without disadvantage. From astronomy we find the
east, west, south, and north, as well as the theory of the heavens, the
equinox, solstice, and courses of the stars. If one has no knowledge of
these matters, he will not be able to have any comprehension of the
theory of sundials.

11. Consequently, since this study is so vast in extent, embellished and
enriched as it is with many different kinds of learning, I think that
men have no right to profess themselves architects hastily, without
having climbed from boyhood the steps of these studies and thus, nursed
by the knowledge of many arts and sciences, having reached the heights
of the holy ground of architecture.

12. But perhaps to the inexperienced it will seem a marvel that human
nature can comprehend such a great number of studies and keep them in
the memory. Still, the observation that all studies have a common bond
of union and intercourse with one another