# Mathematician:Heron of Alexandria

## Mathematician

Heron (or Hero) of Alexandria (Greek: Ἥρων ὁ Ἀλεξανδρεύς) was a Greek mathematician and engineer.

Famous for writing about the aeolipile, otherwise known as Hero's Engine (although he didn't actually invent it), and the device known as Heron's fountain.

Also noted for Heron's Formula for calculating the area of a triangle whose side lengths are known.

Greek

## History

• Born: c. 10 CE, possibly in Alexandria, Egypt
• Died: c. 70 CE

For a long time it was not certain whether Heron had lived in the 1st century BCE or CE, until Otto Neugebauer noticed in $1938$ that he had described an eclipse of the moon such that it had to correspond with a particular lunar eclipse in 62 AD. Hence the question was settled.

## Theorems and Definitions

Results named for Heron of Alexandria can be found here.

Definitions of concepts named for Heron of Alexandria can be found here.

## Publications

• Pneumatica: on machines working on air.
• Automata: on machines for performing so-called wonders in temples.
• Mechanica: on methods of lifting heavy objects.
• Metrica: calculation of surfaces and volumes of various objects.
• On the Dioptra: on methods to measure lengths.
• Belopoeica: on war machines.
• Catoptrica: on the behaviour of light.

These works have at times been attributed to Hero, but the current belief is that they were most likely been written by someone else:

• Geometria: equations based on the first chapter of Metrica.
• Stereometrica: three dimensional calculations based on the second chapter of Metrica.
• Mensurae: tools for making measurements based on Stereometrica and Metrica.
• Cheirobalistra: on catapults.
• Definitiones: definitions of terms for geometry -- this may have been written by Diophantus.

These works exist only in fragments:

• Geodesia
• Geoponica

He is also supposed to have written a commentary on Euclid's The Elements.

## Also known as

Heron and Hero are equally often encountered.