Hero’s Engine: a favorite engine in my collection and the very first steam engine ever devised, the Aeolipile is a radial steam jet reaction turbine, an invention attributed to Hero of Alexandria sometime between 10 and 70 AD. Water within the spherical container is heated to produce steam which exits through nozzles directed at right angles to the radial direction, and by Newton’s third law the steam ejected by these jets produce a torque about the rotation axis. There is no historical record o