Hero Of Alexandria's Timeline Of Accomplishments By Ali Jovinda 85 BCE "Metrica": his study of geometrical techniques for measuring lengths, areas, and volumes. 75 BCE created the idea of "Hero's formula" to calculate a triangle's area. 65 BCE Hero's book "Mechanica" talks about the main features of basic machines like the lever, pulley, and screw. 55 BCE created the aeolipile, a type of steam engine that rotated using steam. 45 BCE Hero's work on mechanisms, such as robot puppets and mechanical singing birds, is named "Automata". 35 BCE "Pneumatica" is Hero's well-known work on pneumatics, which looks at its principles and creates pneumatic devices. Period: 10 BCE to 120 BCE His Inventions