Hero (or Heron) of Alexandria (c. 10-70 AD) was an ancient Greek mathematician and engineer who was active in his native city of Alexandria during the height of the Roman Empire. He is considered the greatest experimenter of antiquity and his work is representative of the Hellenistic scientific tradition. Hero published a well recognized description of a steam-powered device called an aeolipile (hence sometimes called a "Hero engine"). Among his most famous inventions was a windwheel, constituting the earliest instance of wind harnessing on land. He is also said to have been a follower of the Atomists. Much of Hero's original writings and designs have been lost, but some of his works were preserved in Arab manuscripts.It is almost certain that Hero taught at the Musaeum which once included the famous Library of Alexandria, because most of his writings appear as lecture notes for courses in mathematics, mechanics, physics and pneumatics. Although the field was not formalized until the 20th century, it is thought that the work of Hero, his "programmable" automated devices in particular, represents some of the first formal research into cybernetics. The Pneumatica, or Pneumatics of Hero of Alexandria include descriptions of machines working on air, steam or water pressure, including the hydraulis or water organ.