Aeolipile illustration

Hero's Engine or Aeolipile

Hero of Alexandria described construction of the aeolipile (a version of which is known as Hero's engine) which was a rocket-like reaction engine and the first-recorded steam engine (although Vitruvius mentioned the aeolipile in De Architectura some 100 years earlier than Hero). It was created almost two millennia before the industrial revolution. Another engine used air from a closed chamber heated by an altar fire to displace water from a sealed vessel; the water was collected and its weight, pulling on a rope, opened temple doors. Some historians have conflated the two inventions to assert that the aeolipile was capable of useful work.

Hero's Aeolipile in "Death in Vesunna"Edit

The night after the murder of Clodius Eprius, Gaius Tero and Kleandros had dinner together to discuss the strange mysteries in his death. During the discussion of how to speed a lead button fast enough to smash through Eprius' skull, Kleandros recalled a famous artificer from the previous generation named Heron son of Ktesibios from Alexandria. One of his devices was a cauldron with a hollow ball on its lid. The ball had a tube from the cauldron on one side and a pivot on the other. It also had bent nozzles around its circumference. When the cauldron was heated, steam would fill the ball and escape through the nozzles causing the ball to spin. If some way could be found to block the steam for a while and then release it at once, then it could give a small pellet of metal a very strong push, strong enough to kill.[1]


  1. Departures, pgs. 41-42, pb.