7It is now necessary to explain the machine of Ctesibius, which raises water to a height. It is made of brass, and at the bottom are two buckets near each other, having pipes annexed in the shape of a fork, which meet at a basin in the middle. In the basin are valves nicely fitted to the apertures of the pipes, which, closing the holes, prevent the return of the liquid which has been forced into the basin by the pressure of the air.
7Next I must tell about the machine of Ctesibius, which raises water to a height. It is made of bronze, and has at the bottom a pair of cylinders set a little way apart, and there is a pipe connected with each, the two running up, like the prongs of a fork, side by side to a vessel which is between the cylinders. In this vessel are valves, accurately fitting over the upper vents of the pipes, which stop up the ventholes, and keep what has been forced by pressure into the vessel from going down again.