An experimental or educational device comprising a container which can be filled with steam or other heated vapour which escapes through one or more narrow apertures with sufficient force to cause the container to rotate.
Often considered the first steam engine, the aeolipile is said to have been invented by Hero of Alexandria. In his version of the instrument, the water is heated in a cauldron which forms the stand for the ball-shaped vessel.
Mid 17th century; earliest use found in Walter Charleton (1620–1707), physician and natural philosopher. From French éolipile, eolipyle, ?aeolipyle from classical Latin Aeolī pilae pneumatic mechanism or toy, literally ‘doorway of Aeolus’ (Vitruvius 1. 6) from Aeolī, genitive of Aeolus + pilae (from ancient Greek π?λαι, plural of π?λη gate: see -pyle), so called on account of the fact that the vapour bursts from the opening like the winds from the opened door of the cave of Aeolus.