Ctesibius, also known as Ktesibios or Tesibius (Ancient Greek: Κτησίβιος), was a Greek inventor and mathematician who lived in Alexandria, Egypt, during the time of the Ptolemaic rulers. Little is known about his personal life, but his inventions were widely recognized during his lifetime. He may have been the first leader of the Museum of Alexandria. Ctesibius wrote the first books about the science of compressed air and how it could be used in pumps and even a type of cannon. His work on the elasticity of air, described in his book On Pneumatics, earned him the title "father of pneumatics." None of his writings, including a collection of his research called Memorabilia, have survived. However, his most famous invention, the hydraulis (a type of pipe organ), was a precursor to the modern church organ. He was married to a woman named Thais, who should not be confused with Thaïs, a famous companion of Alexander the Great.

Inventions

Ctesibius was born around 300 BCE. He was likely born in Alexandria, though this is not certain. His father was a barber, and Ctesibius began his career in the same profession.

During his time as a barber, he created a mirror that could be adjusted using weights. He also invented the hydraulis, a water-powered musical instrument considered the earliest version of the modern pipe organ and the first keyboard instrument. Ctesibius and his wife, Thais, were known for their skill in playing this instrument. He improved the hydraulis by using the weight of water to force air through the pipes, replacing the use of falling lead weights.

Ctesibius also made improvements to the water clock, or clepsydra, which was previously inaccurate because water flow was hard to control. His version of the water clock remained the most accurate timekeeping device for over 1,800 years until Christiaan Huygens invented the pendulum clock in 1656. He also designed one of the first force pumps to lift water from wells or create a water jet. Examples of these pumps have been found at Roman sites, such as Silchester in Britain.

Ctesibius is also credited with understanding the principle of the siphon and inventing an air-powered catapult using compressed air. His work is known only through writings by Vitruvius and Hero of Alexandria, who used his ideas to develop engineering projects.

Reputation

According to Diogenes Laërtius, Ctesibius was very poor. Laërtius explains this by describing how the philosopher Arcesilaus was affected by Ctesibius’s situation.

Ctesibius’s work is recorded by Vitruvius, Athenaeus, Pliny the Elder, and Philo of Byzantium. These writers mention Ctesibius frequently, noting that early inventors like him had the advantage of working under kings who valued fame and supported artistic and scientific efforts. Proclus, who wrote about Euclid, and Hero of Alexandria also refer to Ctesibius.

In modern times, Ctesibius is not as well known as some other inventors from his era, but he is recognized for helping create future technology and engineering progress. He is called “the father of pneumatics” because of his work with air pressure. His inventions have been improved and used in important ways today.

Commemoration

In 1976, the International Astronomical Union named a crater on the far side of the Moon Ctesibius. In 1897, a group of soft-bodied plant beetles was named Ctesibius by Champion. This group has one known species called C. eumolpoides.