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Ctesibius (Ktesibios)

(fl. Alexandria, 270 b.c.)


Ctesibius lived in Alexandria. The date 270 b.c. is fixed by an epigram by Hedylos, quoted by Athenaeus,1 concerning a singing cornucopia he made for the statue of Arsinoë, the sister and wife of Ptolemy II Philadelphus. Another date, “under Ptolemaeus VII Physkon (145–116 b.c.),” given by Athenaeus2 from Aristokles, has led Susemihl3 and other to assume a second Ctesibius at this date; it seems, however, that the manuscripts are at fault and that Ptolemy I Soter is meant.4

Ctesibius wrote a book about his inventions,5 and Vitruvius,6 who possessed it, tells us that he was the son of a barber. In his father’s shop he hung an adjustable mirror with a counterpoise consisting of a ball of lead descending inside a tube; the ball compressed the air, which escaped with a loud noise.

This showed Ctesibius that the air is a body and led to the invention of the cylinder and the plunger.7 He developed the science of pneumatics, now called hydraulics, probably in collaboration with Strato of Lampsacus,8 who lived in Alexandria until about 288 B. C. Vitruvius praises Ctesibius theoretical introduction to the subject.9

Ctesibius invented an air pump with valves and connected it to a keyboard and rows of pipes;10 this organ is known as the water organ because the air vessel was actuated by water. He also invented a force pump for water.11 Many of the toys described by Philo of Byzantium and Hero of Alexandria in their Pneumatics were taken from Ctesibius’ book; how many we cannot tell, since the book has been lost.

Another invention of Ctesibius’ was the water clock.12 It depends on a clepsydra with constant flow, i.e., a vessel with a hole in the bottom and an overflow, which gives it a constant level and a constant flow through the hole. Ctesibius drilled the hole in gold to avoid rust or verdigris, or in a precious stone to guard against wear; the water flowed into a cylindrical container and lifted a float, which carried a pointer to mark the hours. He equipped the float with a rack turning a toothed wheel and made the clock work a number of parerga: whistling birds, moving puppets, ringing bells, and the like. An attempt to regulate the flow to suit local hours failed, so he constructed the parastatic clock, in which the pointer, moving at a constant rate, marks hours of different length on a network of lines traced on a vertical cylinder, which was turned a little every day.

Philo of Byzantium records two catapults invented by Ctesibius, one actuated by compressed air13 and the other by bronze springs;14 neither seems to have survived him.

Athenaeus the Mechanic15 attributes to Ctesibius a scaling ladder enclosed in a tube, “a marvellous invention, but of no great use.”

Ctesibius was an inventor of the first order; we owe to him the force pumps for air and water and the hydraulic organ with its keyboard and rows of pipes; his water clock has been superseded by the pendulum clock, but his parerga still survive in the cuckoo clock.


1. Athenaeus, Deipnosophistae, bk, 11, p. 497, d–e.

2.Ibid, bk. 4.p.174, b–e.

3. Franz Susemihl, Geschichte der griechischen Litteratur in der Alexandrinerzeit (Leipzig, 1891), 1, 734–736, 775.

4. A. G. Drachmann, “On the Alleged Second Ktesibios,” in Centaurus, 2 (1951), 1–10.

5. Vitruvius, De architectura, bk. 10 ch. 7, v. 5.

6.Ibid., bk, 9, ch. 8, v.2–4.

7. “Philons Belopoiika, Griechisch and Deutsch von H. Diels and E. Schramm,” in Abhandlungen der Preussischen Akademie der Wissenschaften, jahrgang 1918, Phil-hist. Klasse, no. 16 (1919), ch. 61.

8. H. Diels, “Ueber das physikalische System des Straton,” in Sitzungsberichte der K. preussischen Akademie der Wissenschaften zu Berlin, 9 (1893), 106–110.

9. Vitruvius, De architectura, bk. 1, ch.1, v. 7.

10.Ibid., bk. 10, ch. 8.

11.Ibid., ch. 7.

12.Ibid., bk. 9, ch. 8, v. 4–7.

13."Philons Belopoiika,…, “chs. 60–62.

14.Ibid., chs. 14, 39–47.

15. Athenaeus Mechanicus, in C. Wescher, Poliorcetique des Grecs (Paris, 1867). pp. 29–31.


The original work of Ctesibius is lost; excerpts are found in Vitruvius, De architectura, bk. 9, ch. 8; bk. 10, chs. 7–8.

Secondary works not cited in the notes are A. G. Drachmann, Ktesibios, Philon and Heron, no.4 of the series Acta Historica Scientiarum Naturalium et Medicinalium (Copenhagen, 1948); Orinsky, “Ktesibios,” in Pauly-Wissowa, XI, pt. 2 (1922), col. 2074; and Tittel, “Hydraulis,” ibid., IX, pt. 1 (1914), col. 60.

A. G. Drachmann

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Ctesibius (tĬsĬb´ēəs), fl. 2d cent. BC, Alexandrian Greek inventor. He reputedly was the first to discover and apply the expansive power of air as a motive force. Among the inventions ascribed to him are a water clock (clepsydra), a hydraulic organ, and a force pump.