This elegant wooden model, dating from about the late eighteenth century, illustrates a mechanical system that can be used to activate four hydraulic pumps with a single moving axis.
The apparatus represents a liberal interpretation of the patent for a hydraulic device issued to Galileo by the Most Serene Republic of Venice in 1594. In his patent application, the Pisan scientist referred to "a very easy, inexpensive, and very convenient construction for raising water and irrigating land, which, with the motion of a single horse, will cause twenty spouts of water [...] to gush continuously."
The model comprises an inlaid circular platform on which four wells are placed diametrically opposite to one another along the edge. At the center of the platform, a pillar holds a rotating cam, moved by a pair of horses. The cam is connected, by means of four crank arms, to four rocker arms placed on a separate stand. From each arm hangs a chain extending into one of the four wells. The rotary motion of the cam is converted into a to-and-fro motion by the rocker arms. These drive the hydraulic pumps—not included in this model—that draw water from the wells.