or Ktesibios of Alexandria
flourished 0441; 270 BC
Greek physicist and inventor.
He was the first great figure of the ancient engineering tradition of Alexandria, Egypt, which culminated with Heron of Alexandria and Philo of Byzantium. He discovered the elasticity of air and invented several devices using compressed air, including force pump s and an air-powered catapult ; an improvement of the water clock , in which water dripping at a constant rate raised a float with a pointer; and a hydraulus (water organ), in which the weight of water forced air through the organ pipes. His writings have not survived, and his inventions are known only from references to them.