introduction gives a theoretical account of the constitution and properties of matter, and
He ̄ro ̄n argues that air can be compressed and expanded because it consists of small particles
separated by pockets of void. This theory has been associated with S and Epicu-
reanism as well as with E, but the arguments are inconclusive.
Other treatises describe devices for entertainment and show. The Automaton Construction
(Automatika) describes two automatic theaters – one stationary and one moving. At the pull
of a string, the theaters deliver shows featuring moving figures and effects such as lightning
or flames on an altar. One of the shows may reproduce imagery from religious processions,
for instance Dionysos and dancing maenads and the pouring of libations; the other is a
modified version of a show that He ̄ro ̄n ascribes to P B.
Catoptrics (Katoptrika), which discusses reflection in mirrors, is only preserved in a Latin
translation and was first thought to be P’s Optics. Its authenticity has been ques-
tioned, but it almost certainly belongs to an author of He ̄ro ̄n’s school. Catoptrics concerns
the construction of mirror devices such as a street mirror and a trick mirror showing visitors
in a temple an image of a goddess where they expect to see their own reflections. A theor-
etical introduction explains that visual beams are emitted from the eyes and demonstrates
that they are reflected at equal angles in mirrors. He ̄ro ̄n describes how a mirror is manu-
factured and proves geometrically how beams are reflected by different mirrors: plane,
convex, concave, and various cut mirrors. While offering many of the same cases as pseudo-
E’s Optics, He ̄ro ̄n uses a language that indicates he is dealing with actual mirrors as
well as geometrical cases.
A close relationship between geometry and mechanics is also a feature of the Mechanics
(Me ̄khanika), only preserved in an Arabic translation. It opens with a description of the
baroulkos (“weight-lifter”), a box with geared wheels, which can lift a large weight with a
small power; this opening section may derive from an independent treatise on the baroulkos. A
first book concerns various mechanical principles such as geared wheels, the parallelogram
of forces and other problems also treated in the A C M. It
also deals with enlarging or reducing areas proportionally and includes the famous geo-
metrical problem of doubling the cube, i.e. finding the length of the sides of a cube that has
He ̄ro ̄ n of Alexandria: the baroulkos © Reproduced from Drachmann (1963)
HE ̄RO ̄N OF ALEXANDRIA