, is the name of two celebrated mathematicians of antiquity, who are usually distinguished by the epithets, | Hero the elder, and Hero the younger. The first was a native of Alexandria, and the disciple of Ctesias, who flourished in the reigns of Ptolemy Philadelphia and Euergetes I. He was distinguished by his great skill in mechanics, and particularly in the construction of machinery; as a moralist he was inclined to the tenets of Epicurus. He was author of a treatise “De Constructione et Mensura Manubalistoe,” of which a fragment was published in Greek by Bernardino Baldi “Pe Telis conficiendis jaculandisque Liber,” published with notes by Baldi “Spiralia,” published in 1575 by Frederic Commandine and “De Automatorum Fabrica.” These are all to be found in the Louvre edition of the “Ancient Mathematicians.” The younger Hero is supposed to have flourished under the reign of the emperor Heraclius. He was author of “De Machinis Bellicis Geodcesia;” “Liber de Obsidione repellenda et toleranda” and <c De Vocabulis Geonaetricis et Stereometricis." 1

1 Dict. ttist Fabric. Uibl. Grcec. Saxii Quomast.