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Hero of Alexandria

Hero (or Heron) of Alexandria (roughly A.D. 10 to roughly A.D. 70) was a Greek engineer and geometer. His most famous invention was the first documented steam engine, the aeolipile. He is said to have been a follower of the Atomists. Some of his ideas were derived from the works of Ctesibius.

A number of references mention dates around 150 BC, but these are inconsistent with the dates of his publications and inventions. Perhaps this is due to a misinterpretation of the phrase "first century".

Table of contents
1 Publications
2 Projects
3 References


The complete surviving works are: In optics, Hero proposed that light travels along the shortest geometric path. This view is no longer accepted, having been replaced by the least-time principle.

In geometry, he stated and proved a formula, now known as Heron's formula, for calculating the area of a triangle in terms of its sides.



The Technology Museum of Thessaloniki has a good web page on Hero at