In folio 1068v, we find a quick sketch of a machine made up of an Archimedean screw on which is mounted a retractable wheel fed by the water raised by the screw before being conveyed on another hydraulic wheel, which gives power to the millstones of a mill. The same type of engine, without any ‘mechanical user’ and with a vertical hydraulic wheel instead of a horizontal mill wheel, is illustrated in folio 1069v.