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.
2Above the basin is a cover like an inverted funnel, fitted and fastened to it with a rivet, that the force of the water may not blow it off. On this a pipe, called a trumpet, is fixed upright. Below the lower orifices of the pipes the buckets are furnished with valves over the holes in their bottoms.
3Pistons made round and smooth, and well oiled, are now fastened to the buckets, and worked from above with bars and levers, which, by their alternate action, frequently repeated, press the air in the pipes, and the water being prevented from returning by the closing of the valves, is forced and conducted into the basin through the mouths of the pipes; whence the force of the air, which presses it against the cover, drives it upwards through the pipe: thus water on a lower level may be raised to a reservoir, for the supply of fountains.
4Nor is this the only machine which Ctesibius has invented. There are many others, of different sorts, which prove that liquids, in a state of pressure from the air, produce many natural effects, as those which imitate the voices of singing birds, and the engibita, which move figures that seem to drink, and perform other actions pleasing to the senses of sight and hearing.
5From these inventions I have selected those which are most pleasing and necessary, and described them in my treatise on dialling: in this place I confine myself to those which act by the impulse of water. The others, which are more for pleasure than utility, may be seen by the curious in the writings of Ctesibius.