Two points here are specially worthy of attracting our attention, and these are the flow of wine or milk from the statue of Bacchus, and the spontaneous lighting of the altar. These, in fact, were the two illusions that were most admired in ancient times, and there were several processes of performing them. Father Kircher possessed in his museum an apparatus which he describes in “Œdipus Ægyptiacus” (t. ii., p. 333), and which probably came from some ancient Egyptian temple as shown in [Fig. 6].
It consisted of a hollow hemispherical dome, supported by four columns, and placed over the statue of the goddess of many breasts. To two of these columns were adapted movable brackets, at whose extremities there were fixed lamps. The hemisphere was hermetically closed underneath by a metal plate. The small altar which supported the statue, and which was filled with milk, communicated with the interior of the statue by a tube reaching nearly to the bottom. The altar likewise communicated with the hollow dome by a tube having a double bend. At the moment of the sacrifice the two lamps were lighted and the brackets turned so that the flames should come in contact with and heat the bottom of the dome. The air contained in the latter, being dilated, passed through the tube X M and pressed on the milk contained in the altar, and caused it to rise through the straight tube into the interior of the statue as high as the breasts. A series of small conduits, into which the principal tube divided, carried the liquid to the breasts, whence it spurted out, to the great admiration of the spectators, who cried out at the miracle. The sacrifice being ended, the lamps were put out, and the milk ceased to flow.
Heron of Alexandria describes in his “Pneumatics” several analogous apparatus. Here is one of them. (M. de Rochas translates the Greek text literally.)
“To construct an altar in such a way that, when a fire is lighted thereon, the statues at the side of it shall make libations ([Fig. 7]).
“Let there be a pedestal, Α Β Γ Δ, on which are placed statues, and an altar, Ε Ζ Η, closed on every side. The pedestal should also be hermetically closed, but is connected with the altar through a central tube. It is traversed likewise by the tube, e Λ (in the interior of the statue to the right), not far from the bottom, which terminates in a cup held by the statue, e. Water is poured into the pedestal through a hole, Μ, which is afterward corked up.
FIG. 8.—MARVELOUS ALTAR (ACCORDING TO HERON).
“If, then, a fire be lighted on the altar, the internal air will be dilated, and will enter the pedestal and drive out the water contained in it. But the latter, having no other exit than the tube, e Λ, will rise into the cup, and so the statue will make a libation. This will last as long as the fire does. On extinguishing the fire the libation ceases, and occurs anew as often as the fire is relighted.
“It is necessary that the tube through which the heat is to introduce itself shall be wider in the middle; and it is necessary, in fact, that the heat, or rather that the draught that it produces, shall accumulate in an inflation, in order to have more effect.”