We know nothing biographical about Hero of Alexandria. Even his dates are unknown, but internal evidence suggests that he was writing about 62 A.D. It is not even clear if he invented the two devices which bear his name: Hero's Fountain and Hero's Engine.     Hero's Engine is today a generic name for any device which propels itself by shooting steam from one or more orifices. These devices are also known as Eolipiles.     The two engines in the picture at the left are from the apparatus collection at Yale University. After filling the sphere with water, a flame is applied to it until the water boils, and the device begins to rotate.

   The Eoliopile at Amherst College at the left below was sold by Queen of Philadelphia for $8.00. It is listed in the 1881 catalogue as "Hero's Engine. With straight jet, mounted, with lamp, on a neat car." All 19th century apparatus catalogues listed Hero's engines, and I have never seen one with a maker's mark.
                                 Amherst College                                                                         Union College

The Hero's engine at the right is mounted on a steam boiler. It was made by Millington of London, and in the museum at the University of Mississippi.

The three-jet Hero's engine at the right is in the Greenslade Collection. It was mad by Leybold of Cologne, Germany, and is listed in the 1921 catalogue at $6.00. The imported for Leybold apparatus at this time was James W. Biddle of Philadelphia.