The successive lighting of the two altars, the flow of milk and wine, and the noise of drums and cymbals were likewise obtained by the aid of cords moved by counterpoises, and the lengths of which were graduated in such a way as to open and close orifices, at the proper moment, by acting through traction on sliding valves which kept them closed.
Small pieces of combustible material were piled up beforehand on the two altars, the bodies of which were of metal, and in the interior of which were hidden small lamps that were separated from the combustible by a metal plate which was drawn aside at the proper moment by a small chain. The flame, on traversing the orifice, thus communicated with the combustible.
The milk and wine which flowed out at two different times through the thyrsus and cup of Bacchus came from a double reservoir hidden under the roof of the temple, over the orifices. The latter communicated, each of them, with one of the halves of the reservoir through two tubes inserted in the columns of the small edifice. These tubes were prolonged under the floor of the stage, and extended upward to the hands of Bacchus. A key, maneuvered by cords, alternately opened and closed the orifices which gave passage to the two liquids.
As for the noise of the drums and cymbals, that resulted from the falling of granules of lead, contained in an invisible box provided with an automatic sliding-valve, upon an inclined tambourine, whence they rebounded against little cymbals in the interior of the base of the car.
FIG. 2.--MARVELOUS ALTAR (According to Heron).
Finally, the crowns and garlands that suddenly made their appearance on the four faces of the base of the stage were hidden there in advance between the two walls surrounding the base. The space thus made for the crowns was closed beneath, along each face, by a horizontal trap moving on hinges that connected it with the inner wall of the base, but which was held temporarily stationary by means of a catch. The crowns were attached to the top of their compartment by cords that would have allowed them to fall to the level of the pedestal, had they not been supported by the traps.
At the desired moment, the catch, which was controlled by a special cord, ceased to hold the trap, and the latter, falling vertically, gave passage to the festoons and crowns that small leaden weights then drew along with all the quickness necessary.
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 Oedipus Egyptiacus (t. ii., p. 333), and which probably came from some ancient Egyptian temple. (Fig. 1.)
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, issued through the tube, X M, 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. (We translate the Greek text literally.)
Fig. 3.--MARVELOUS ALTAR (According to Heron).
"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. 2.)
"Let there be a pedestal. A B Γ Δ, on which are placed statues, and an altar, E Z H, closed on every side. The pedestal should also be hermetically closed, but is communicated 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, M, which is afterward corked up.
"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."
According to Father Kircher (l. c.), an author whom he calls Bitho reports that there was at Sais a temple of Minerva in which there was an altar on which, when a fire was lighted, Dyonysos and Artemis (Bacchus and Diana) poured milk and wine, while a dragon hissed.
It is easy to conceive of the modification to be introduced into the apparatus above described by Heron, in order to cause the outflow of milk from one side and of wine from the other.
After having indicated it, Father Kircher adds: "It is thus that Bacchus and Diana appeared to pour, one of them wine, and the other milk, and that the dragon seemed to applaud their action by hisses. As the people who were present at the spectacle did not see what was going on within, it is not astonishing that they believed it due to divine intervention. We know, in fact, that Osiris or Bacchus was considered as the discoverer of the vine and of milk; that Iris was the genius of the waters of the Nile; and that the Serpent, or good genius, was the first cause of all these things. Since, moreover, sacrifices had to be made to the gods in order to obtain benefits, the flow of milk, wine, or water, as well as the hissing of the serpent, when the sacrificial flame was lighted, appeared to demonstrate clearly the existence of the gods."
In another analogous apparatus of Heron's, it is steam that performs the role that we have just seen played by dilated air. But the ancients do not appear to have perceived the essential difference, as regards motive power, that exists between these two agents; indeed, their preferences were wholly for air, although the effects produced were not very great. We might cite several small machines of this sort, but we shall confine ourselves to one example that has some relation to our subject. This also is borrowed from Heron's Pneumatics. (Fig. 3.)
"Fire being lighted on an altar, figures will appear to execute a round dance. The altars should be transparent, and of glass or horn. From the fire-place there starts a tube which runs to the base of the altar, where it revolves on a pivot, while its upper part revolves in a tube fixed to the fire-place. To the tube there should be adjusted other tubes (horizontal) in communication with it, which cross each other at right angles, and which are bent in opposite directions at their extremities. There is likewise fixed to it a disk upon which are attached figures which form a round. When the fire of the altar is lighted, the air, becoming heated, will pass into the tube; but being driven from the latter, it will pass through the small bent tubes and ... cause the tube as well as the figures to revolve."
Father Kircher, who had at his disposal either many documents that we are not acquainted with, or else a very lively imagination, alleges (Oedip. aeg., t. ii., p. 338) that King Menes took much delight in seeing such figures revolve.
Nor are the examples of holy fire-places that kindled spontaneously wanting in antiquity.
Pliny (Hist. Nat., ii., 7) and Horace (Serm., Sat. v.) tell us that this phenomenon occurred in the temple of Gnatia, and Solin (Ch. V.) says that it was observed likewise on an altar near Agrigentum. Athenaeus (Deipn. i., 15) says that the celebrated prestidigitator, Cratisthenes, of Phlius, pupil of another celebrated prestidigitator named Xenophon, knew the art of preparing a fire which lighted spontaneously.
Pausanias tells us that in a city of Lydia, whose inhabitants, having fallen under the yoke of the Persians, had embraced the religion of the Magi, "there exists an altar upon which there are ashes which, in color, resemble no other. The priest puts wood on the altar, and invokes I know not what god by harangues taken from a book written in a barbarous tongue unknown to the Greeks, when the wood soon lights of itself without fire, and the flame from it is very clear."
The secret, or rather one of the secrets of the Magi, has been revealed to us by one of the Fathers of the Church (Saint Hippolytus, it is thought), who has left, in a work entitled Philosophumena, which is designed to refute the doctrines of the pagans, a chapter on the illusions of their priests. According to him, the altars on which this miracle took place contained, instead of ashes, calcined lime and a large quantity of incense reduced to powder; and this would explain the unusual color of the ashes observed by Pausanias. The process, moreover, is excellent; for it is only necessary to throw a little water on the lime, with certain precautions, to develop a heat capable of setting on fire incense or any other material that is more readily combustible, such as sulphur and phosphorus. The same author points out still another means, and this consists in hiding firebrands in small bells that were afterward covered with shavings, the latter having previously been covered with a composition made of naphtha and bitumen (Greek fire). As may be seen, a very small movement sufficed to bring about combustion.--A. De Rochas, in La Nature.