VITRUVIUS.
In the length of this (canon) are channels (V), in number four if tetrachordic, six if hexa¬
chordic, and eight if octachordic. In the several channels are epistomia (stoppers) (P), having
iron handles (Q); which handles, when turned, open orifices (O) from the arca (arcula) into
the channels. The canon has also holes (R) ranged transversely, communicating with the
channels, and corresponding to orifices (S) in the upper table, which in Greek is called pinax.
Between the table and canon are disposed rulers (T), which being perforated in the same
manner, and anointed with oil that they may be easily moved to and fro, stop these holes,
and are called pleuritides; the passing and repassing of which alternately stops and opens the
holes.
These rulers have iron choragia (U) affixed to them, and are united to pinnae (WVX), the
touching of which pinnae causes the motion of the rulers. Upon the table are the holes (S)
through which the air from the channels passes. To the rulers are fixed rings, in which the
tongues of all the organic pipes (Y) are inclosed. From the buckets (D) proceed tubes (Z).
united to the neck of the pnigeus, and communicating with the orifices that are in the arcula:
in these tubes are fixed well-turned valves (a), which, when the arcula has received the air.
stop their apertures, and prevent its return.
Thus, when the handles of the levers (G) are raised, the pistons of the buckets are drawn
to the bottom; and the dolphins that are fixed on axes lowering the cymbals that hang from
(3*) I am of opinion that arcula should be here read
instead of arca; for it is with the former that the chan-
nels immediately communicate, as has been just ex¬
pressed.
(4*) This word is written plintbides in all the manu¬
scripts that I have seen; although all the printed editions
have pleuritides, as here written.
(52) Vitruvius explains not what he means by cboragia
which in Greek signifies dancers. The commentators
suppose some kind of springs are intended by that word:
and this supposition seems to be well founded; for, by
the description of Heron, it appears that a curved flat
piece of horn U (Vitruvius says, iron) was fixed before
each ruler, and a string (of gut) V tied from the end of
this horn spring to the rulers T; which latter, when driven
backward by the pressure of the hand on the pinnae X.
was by this means drawn forward again as soon as that
pressure was removed.
Hleron allo gives us the description of the pinna, which
Viruvius has omitted. Theywere inthe form of a ficht
angle VWX; the perpendicular leg VW was joined at its
lower end V to the ruler, with a moveable joint, and it also
turned on an axis at its angle W: when therefore the end X
was pressed down, it caused the ruler to move backward;
so that the holes TT in the ruler, coincided with the holes
R and 8 in the canon and upper table, and by that means
admitted the air from the channels to pass into the pipes
Y T, thus causing them to sound. But when the pressure
at the end X was removed, the horn spring U drew the
ruler back again to its former place; and thus, the holes
7 in the ruler, no longer coinciding with those of R and S,
the mouths of the pipes were thereby stopped; so that
by pressing down the pinnæ (or keys, as we call them),
in the same manner as in our modern organs, the pipes
were caused to sound.
(6*) Turnebus here also alters ligneis cervicibus, collars
of wood, to pnigei cervicis, the collar of the pnigéus; and
lignea, a little farther on, to pnigea. The correction is
generally received by the translators; and appears to be
right, for the reasons before mentioned.