Hero steam engine. Artwork of the steam engine devised by 1st-century AD Greek engineer Hero of Alexandria. The device is also called an aeolipile. The fire underneath heats water in the main chamber to produce steam. This emerges from the nozzles on the hollow sphere (top) that is free to rotate about an axis. It is not thought the device had any practical use, but was used in temples as a device to produce wonder and awe in visitors.