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, O 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. 30. _An Automaton which will drink any quantity that may be presented to it._ [Illustration: Diagram of apparatus as described in text] The animal may be made to drink without the aid of running water, or of any thing to move the figure of Pan. Let A B C D (fig. 30) be a pedestal, and E the mouth of the animal, through the breast and hinder foot or tail of which a tube, E F G, is inserted, leading from the mouth E to the interior of the pedestal. The pedestal having been first firmly fixed, let a hole, E, so fine as to be scarcely discernible, be bored in the tube E F G which passes through the animal, in a line with the extremity G. Now if we fill the siphon E F G with water through some pipe above it, the mouth of which is applied to E, the siphon will continue full since its two orifices lie in the same level. If, therefore, a drinking vessel be brought to the mouth E, and a portion of the mouth immersed in it, it will be found that the leg of the siphon towards G has become the longer, so that it will attract the water, and the water attracted is carried into the pedestal A B C D. In this construction it is not necessary that A B C D should be air-tight. 31. _A Wheel in a Temple, which, on being turned, liberates purifying Water._