Hero, of Alexandria
- Georgia L. Irby-Massie
Greek polymath who worked in mathematics, astronomy, and mechanics. He is especially famous for descriptions of automata (air-, water-, and steam-powered mechanical devices) and steam-powered aeolipiles. “Hero’s engine,” deriving from Ctesibius of Alexandria’s design (290–250 bce), is the first device to transform steam into rotary motion. The aeolipile consists of a hollow sphere attached by pipes to an enclosed water-filled cauldron. When the cauldron is heated, the sphere spins on a pivot as it releases steam (Pneumatics 50).
Hero’s much disputed floruit was pinpointed by Neugebauer (1975, 846), who noted that Hero used eyewitness evidence of a lunar eclipse of 62 ce, visible from both Rome and Alexandria, to calculate the distance between those two cities (Dioptra 35). Making no use of Ptolemy of Alexandria (127–after 146 ce Hero likely predated Ptolemy Neugebauer Very little is known of Hero s life His mathematical corpus ...
A version of this article originally appeared in The Dictionary of African Biography.