1 The Birth of Science - MSRI

4.9 Heron’s Role 111
cle to another representing the sidereal revolution of the moon, according
to the ratio of 254 lunar revolutions to 19 solar years.
Technologically speaking two features stand out. One is the complexity
of the mechanism, which uses at least thirty gears. This intricacy is what
makes one instinctively assign the machine to the category of clockwork.
The second and most remarkable feature is the presence of a differential page 152
turntable, a mechanism that allows the addition or subtraction of angular
velocities. The differential was used to compute the synodic lunar cycle
(moon phase cycle), by subtracting the effects of the sun’s movement from
those of the sidereal lunar movement.
Price’s verdict about the significance of the Antikythera mechanism is
revealing: “We must suppose that from both Heron and Vitruvius we underestimate
what was available in gearing technology in their times.” 116a
Indeed, he felt that the existence of this single object of “high technology”
is enough to radically alter our ideas about classical civilization and lay
to rest once and for all old clichés to the effect that the Greeks scorned
technology and that the easy availability of slave labor led to an unsurmountable
gap between theory and experimental and applied sciences. 117
4.9 Heron’s Role
The most famous written documentation on Hellenistic technology that
has survived consists of the works of Heron of Alexandria. Heron, who
lived most likely in the first century of our era, 118 described a great many
“marvelous engines”, especially in two of his works: the Pneumatica and
the Automata. They include, for example, a vending machine, which, upon
the introduction of a five-drachma coin, would dispense a fixed amount of
liquid. 119 The ones that evoke the greatest wonder in the modern reader
are perhaps those that constituted the automatic theater. 120 Each playlet, page 153
enacted by automata, was subdivided into scenes; between scenes the
116a [Price: Gears], p. 54.
117 [Price: SSB], p. 42; [Price: Gears], p. 51. Price’s comments seem to be informed by a personal experience;
he held very different views on Greek technology in [Price: Instruments], written twenty
years earlier.
118 The most useful datum for dating Heron is the lunar eclipse used as an example in the Dioptra,
which was unequivocally identified as that of March 13, 62 A.D. in [Neugebauer: Heron]. Heron
might conceivably be transmitting an account of an earlier author, but it is likely that he used a
recent eclipse. In any case 62 A.D. is a terminus post quem. The dating once proposed as the most
probable by Heiberg and Heath, namely the third century A.D., is excluded by the fact that Sextus
Empiricus, around 200 A.D., seems to refer to Heron, though not by name (see pages 283–284).
119 Heron, Pneumatica, I, xxi.
120 Heron, Automata.
Revision: 1.14 Date: 2002/10/24 04:25:47