Hero(or Heron) of Alexandria was a Greek mathematician and engineer whose major contributions to mathematics were Hero's formulaand the first approximation in Greece of a number's square root. He also wrote a number of books on mathematics, including Metrica, is a treatise on geometry. While much of his writings in mathematics and mechanics stem from earlier authors, Hero is credited as being one of the earliest and most comprehensive and detailed recorders of ancient technology, especially through such works as Penumaticaand Automata. Hero also designed many mechanical instruments, which earned him the name "the mechanic" or "the machine man."

Other than his writings, nothing is known about the life of Hero, who is sometimes referred to as Heron. The date of his birth is unknown, and estimates of when he lived vary by 150 years. However, Hero mentions an eclipse of the moon visible from Alexandria in...