Ctesibius

Ctesibius, also known as Ktesibios or Tesibius (fl. 285–222 BC), was an Egyptian inventor and mathematician in Alexandria, Ptolemaic Egypt. He wrote treatises on the science of compressed air and its uses in pumps. He also wrote about pneumatics, including the elasticity of air, in his treatise On pneumatics. None of his written work has survived, including his Memorabilia, a compilation of his research that was cited by Athenaeus.

Inventions

Ctesibius was probably the first head of the Museum of Alexandria. Very little is known of his life but his inventions were well known. It is said (possibly by Diogenes Laertius) that his first career was as a barber. During his time as a barber, he invented a clever counterweight-adjustable mirror. His other inventions include the hydraulis, a water organ that is considered the precursor of the modern pipe organ, and an improved water clock called a clepsydra. The clepsydra kept more accurate time than any clock invented until the Dutch physicist Christiaan Huygens detailed the use of a pendulum to regulate a clock in the 17th century. He described one of the first force pumps for producing a jet of water, or for lifting water from wells, and examples have been found at various Roman sites, such as at Silchester in Britain. The principle of the siphon has also been attributed to him.

According to Diogenes Laertius, Ctesibius was miserably poor. Laertius details this by recounting the following concerning the philosopher Arcesilaus:

"when he had gone to visit Ctesibius who was ill, seeing him in great distress from want, he secretly slipped his purse under his pillow; and when Ctesibius found it, 'This,' said he, 'is the amusement of Arcesilaus.'" [1]

Reputation

Ctesibius's work is chronicled by Vitruvius, Athenaeus, and Philo of Byzantium who repeatedly mentions him, adding that the first mechanicians such as Ctesibius had the advantage of being under kings who loved fame and supported the arts. Proclus (the commentator on Euclid) and Hero of Alexandria (the last of the engineers of antiquity) also mention him.