There is another way in which, by the aid of running water, the animal may be made to drink on the revolution of a carved figure of Pan. Let A B C D (fig. 29) be a pedestal, air-tight on every side, and divided into two chambers by a partition.
On the surface place the animal, and let
the tube E F G pass through its mouth. Within the pedestal,in the lower
chamber, let there be a bent siphon, H K L, the lower leg projecting
from the bottom: and let a funnel, M N, pass through the middle of the
partition, its tube reaching nearly to the bottom. On the pedestal A B C
D place another pedestal, 0 X, on which the figure of Pan, P R, is to
stand, having attached to it the rod S which projects below into the
pedestal. To S let the tube T U be fastened, at the end of which is the
cup U Q, attached to and communicating with the tube. Let the tube be of
such a length that, when the figure P R turns round, the cup U Q will be
directly above the funnel M N. On the pedestal, and communicating with
it, and directly above the funnel M N, place the cup W Y. Let the stream
Z, (which must be greater than the discharge through the siphon H K L),
flow into W Y: the liquid will pass through M N into the lower part of
the pedestal, the contained air passing out through E F G: and now the
pedestal will continue full as the influx is greater than the discharge.
But, when we turn the figure P R round, the cup U Q will intercept the
stream Z, which will pass elsewhere through the tube T U, and, as the
water no longer flows into the lower chamber of the pedestal, the siphon
H K L will empty it, and the air will enter through E F G. Thus, when
the cup is applied, the animal will drink as before.