The engineer, mathematician, and inventor Heron of Alexandria (active ca. AD 60) ranks among the most important scientists of the ancient Roman world in the tradition of Aristotelian experimentation.

Heron, about whose personal life virtually nothing is known, resided in Alexandria, Egypt, among the scientists and men of letters of the late Ptolemaic and Roman eras who dwelled around the famed library and museum. A brilliant theoretical scientist and a prolific writer, Heron wrote with clarity and insight. The knowledge of his writings and scientific investigations was preserved in the writings of the late Roman, Byzantine, and Arabic scientists and encyclopedists.

One of Heron's outstanding treatises was the Metrica, a geometrical study, in three volumes, on the measurement of simple plane and solid figures from polygons to hendecagons. It approximates the areas of triangles, polygons, quadrilaterals, ellipses, spheres, circles, and cones, and the volumes of various solids, including the cone, cylinder, and pyramid. In developing the mathematical studies, Heron solved complex quadratic equations arithmetically, approximated the square roots of nonsquare numbers, and calculated cube roots. Heron's other mathematical works include the Definitions, Geometrica, Geodaesia (Land Measurements), Stereometrica (Solid Measurement), Mensurae (Measures), and Liber geëponicus (Book on Agriculture).

In the Mechanica, preserved only in Arabic, Heron explored the parallelograms of velocities, determined certain simple centers of gravity, analyzed the intricate mechanical powers by which small forces are used to move large weights, discussed the problems of the two mean proportions, and estimated the forces of motion on an inclined plane. The Pneumatica, possibly derived from the works of Philo of Byzantium and Ctesibus, describes mechanical devices operated by compressed air, water, or steam. Included are the steam engine, siphon, fire engine, water organ, slot machines, and water fountains. Other works by Heron dealing with the problems of mechanics and engineering are the Barulcus (On Raising Heavy Weights), Belopoeica (Making Darts), On Automaton-making, Catoptrica (On Mirrors), and On the Dioptia. In the last treatise Heron describes a machine called the "Cheirobalistra," which depended on a refined screw-cutting technique and could be used to bore a tunnel through a mountain. He also described an instrument called the hodometer for measuring distances traveled by wheeled vehicles.

Beyond gadgetry, the practical application of Heron's ideas in antiquity was minimal, although they did influence Arabic and Renaissance construction of fountains, clocks, and automated objects. In Heron's time the widespread use of slave labor throughout the Roman world negated most interests in labor-saving devices.

Further Reading

• Some fragments of Heron's writings appear in English in Morris R. Cohen and Israel E. Drabkin, A Source Book in Greek Science (1958). Heron's scientific ideas are best presented in A. G. Drachman, The Mechanical Technology of Greek and Roman Antiquity (1963), and Robert S. Brumbaugh, Ancient Greek Gadgets and Mechanics (1966). General books which discuss Heron and ancient science are Marshall Clagett, Greek Science in Antiquity (1955), and L. Sprague de Camp, The Ancient Engineers (1963).