Aeolipyle

Part of speech: noun

Pronunciation: /ˈiːəʊlɪpʌɪl/

Definitions

1. A mechanical device that utilizes steam to generate rotary motion
2. An engine that transforms the energy from steam into rotational energy for various applications
3. A device that creates spinning motion by ejecting steam from nozzles attached to a rotating sphere

Etymology: The aeolipile is named for Aeolus, keeper of the winds in Greek myth, and the device was built to show that wind-power in its purest form was steam. Its best-known description comes from Hero of Alexandria, the Greek engineer, who described a hollow sphere mounted on pipes that spun when steam jetted out of them. The name joins Latin "Aeoli pylae," meaning "doorway of Aeolus," so the sphere was imagined as a little gateway through which the winds escaped. Hero's contraption was a curiosity rather than a working engine, and for centuries it remained a toy of philosophers and engineers. The name arrived in English through French "éolipyle," which carried the classical reference across with it, so the word preserves a mythological doorway that the device itself never really opened onto anything practical.