previous next


CTESI´BICA MA´CHINA a hydraulic engine named after its inventor, Ctesibius of Alexandria, quiet vim spiritus naturalis pneumaticasque res invenit (Vitr. 9.9 (8), § 2). In the language of modern hydraulics it is a doubleactioned forcing pump. Vitruvius in his description (10.10 (7)), speaks of it as designed to raise water, while Ctesibius' pupil Hero (Pneumat. p. 180) describes, under the name of σίφων, a machine identical in principle, but of improved construction, and says that it was used as a fire-engine (εἰς τοὺς ἐμπρησμούς). Indeed the same principle is employed in our modern fire-engines. The remains of such a σίφων were discovered at Castrum Novum, near Cività Vecchia, in 1795 (Schneider on Vitruv. l.c.), having probably served to supply the public baths with water.

The following cut illustrates the construction of Ctesibius' invention as described by Vitruvius. Two cylinders (modioli) B B are connected by pipes with a receiver (catinus) A, which is closed by a cowl (paenula) D. In each cylinder a piston (embolus masculus) C is worked by means of its rod (regula): in the bottom of each cylinder, and at the opening

Ctesibica Machina. (Rich.)

of each pipe into the receiver, is a movable lid or valve (assis), which only opens upwards. The bottoms of the cylinders are inserted into a reservoir, or connected with it by pipes. When one of the pistons is raised, a vacuum is produced in the cylinder, and the atmospheric pressure forces a stream of water past the raised valve into the cylinder. When this stream ceases, the valve falls; and if the piston is forced down, the water is driven out of the cylinder into the pipe, and past the valve into the receiver, and retained there by the closing of the valve. If the two pistons are worked alternately, so that one descends as the other rises, a continuous stream of water is forced out of the top of the paenula.

If we turn to the accompanying illustrations from the pump found at Castrum Novum and to Hero's description, we find the cylinders (πυξίδες) A A, with their valves (ἀσσάρια) FF, the pistons (ἐμβολεῖς), as B, the piston--rods (κανόνια), as C, identical with those described above; but in place of the pipes a horizontal tube D with

Ctesibica Machina. (Rich.)

valves F F is used, and in place of the catinus a vertical tube (σωλὴν ὄρθιος) E. It is clear, however, that these improvements in construction do not affect the principle of the machine or the mode of its working. (Plin. Ep. [p. 1.571]10.42, 2; Isid. Or. 20.6, 9; Dig. 33, 7, 12.18.)


hide Display Preferences
Greek Display:
Arabic Display:
View by Default:
Browse Bar: