Study of self-powered water-lifting machines
The same type of engine sketched on folio 1068v, without any ‘mechanical user’ and with a vertical hydraulic wheel instead of a horizontal mill wheel, is illustrated in folio 1069v. On the same sheet Leonardo also explores the idea of a machine capable of self-powering and imagines mounting in sequence four devices, each consisting of an Archimedean screw and a hydraulic wheel, in which the wheels are positioned along the same mill pond at decreasing heights, so as to be powered in succession by the same watercourse. He seems to be well aware that the problem with this type of machine consists in being able to produce a surplus of energy compared to that needed to put it in motion; with this solution, on paper, he was able to raise in the supply tank a volume of water four times bigger than the necessary and that could be ‘virtually’ used to drive other devices. Leonardo, who seems to have been very interested in this project, on the same sheet draws a four-screw device integrated with a priming system consisting of a chain pump and a weight motor, which has the task of lifting the initial amount of water to start the machine.