In half a dozen chapters mechanical birds are made to sing by driving air through a pipe by the pressure of flowing water. In other chapters a dragon is made to hiss and a thyrsus to whistle by similar methods. By the force of compressed air water is made to spurt forth and automatons to sound trumpets. The heat of the sun’s rays is used to warm air which expands and causes water to trickle out. In a number of cases as long as a fire burns on an altar the expansion of enclosed air caused thereby opens temple doors by the aid of pulleys, or causes statues to pour libations, dancing figures to revolve, and a serpent to hiss. The force of steam is used to support a ball in mid-air, revolve a sphere, and make a bird sing or a statue blow a horn. Inexhaustible lamps are described as well as inexhaustible goblets, and a self-trimmed lamp in which a float resting on the oil turns a cog-wheel which pushes up the wick as it and the oil are consumed. Floats and cog-wheels are also used in some of the tricks already mentioned. In another the flow of a liquid from a vessel is regulated by a float and a lever. Cog-wheels are also employed in constructing the neck of an automaton so that it can be cut completely through with a knife and yet the head not be severed from the body. A cupping glass, a syringe, a fire engine pump with valves and pistons, a hydraulic organ and one worked by wind pretty much exhaust the contents of the Pneumatics. In its introduction Hero alludes to his treatise in four books on water-clocks, but this is not extant. Hero’s water-organ is regarded as more primitive than that described by Vitruvius.[893]
Magic mirrors.
If magic jugs and marvelous automatons make up most of the contents of the Pneumatics and Automatic Theater, comic and magic mirrors play a prominent part in the Catoptrics. The spectator sees himself upside down, with three eyes, two noses, or an otherwise distorted countenance. By means of two rectangular mirrors which open and close on a common axis Pallas is made to spring from the head of Zeus. Instructions are given how to place mirrors so that the person approaching will see no reflection of himself but only whatever apparition you select for him to see. Thus a divinity can be made suddenly to appear in a temple. Clocks are also described where figures appear to announce the hours.
Astrology and occult virtue.
Hero displays a slight tendency in the direction of astrology, discussing the music of the spheres in the first chapters of the Catoptrics, and in the Pneumatics describing an absurdly simple representation of the cosmos by means of a small sphere placed in a circular hole in the partition between two halves of a transparent sphere of glass. One hemisphere is to be filled with water, probably in order to support the ball in the center.[894] The marvelous virtues of animals other than automatons are rather out of his line, but he alludes to the virtue of the marine torpedo which can penetrate bronze, iron, and other bodies.
Date of extant Greek alchemy.
Although we have seen some indications of its earlier existence in Egypt, alchemy seems to have made its appearance in the ancient Greek-speaking and Latin world only at a late date. There seems to be no allusion to the subject in classical literature before the Christian era, the first mention being Pliny’s statement that Caligula made gold from orpiment.[895] The papyri containing alchemistic texts are of the third century, and the manuscripts containing Greek works of alchemy, of which the oldest is one of the eleventh century in the Library of St. Mark’s, seem to consist of works or remnants of works written in the third century and later, many being Byzantine compilations, excerpts, or additions. Also Syncellus, the polygraph of the eighth century, gives some extracts from the alchemists.
Legend that Diocletian burned the books of the alchemists.
Syncellus and other late writers[896] are our only extant sources for the statement that Diocletian burned the books of the alchemists in Egypt, so that they might not finance future revolts against him. If the report be true, one would fancy that the imperial edict would be more effective as a testimonial to the truth of transmutation in encouraging the art than it would be in discouraging it by destroying a certain amount of its literature. Thus the edict would resemble the occasional laws of earlier emperors banishing the astrologers—except their own—from Rome or Italy because they had been too free in predicting the death of the emperor, which only serve to show what a hold astrology had both on emperors and people. But the report concerning Diocletian sounds improbable on the face of it and must be doubted for want of contemporary evidence. Certainly we are not justified in explaining the air of secrecy so often assumed by writers on alchemy as due to the fear of persecution which this action of Diocletian[897] or the fear of being accused of magic aroused in them. Persons who wish to keep matters secret do not rush into publication, and the air of secrecy of the alchemists is too often evidently assumed for purposes of show and to impress the reader with the idea that they really have something to hide. Sometimes the alchemists themselves realize that this adoption of an air of secrecy has been overdone. Thus Olympiodorus wrote in the early fifth century, “The ancients were accustomed to hide the truth, to veil or obscure by allegories what is clear and evident to everybody.”[898] Nor can we accept the story of Diocletian’s burning the books of alchemy as the reason why none have reached us which can be certainly dated as earlier than the third century.
Alchemists’ own accounts of the history of their art.