Studies of perpetual engines based on the Archimedean screw

On this sheet Leonardo develops the topic of the Archimedean screw in self-propelled systems capable of rotating in perpetual motion. The idea is to combine two concentric scrolls with different diameters and winding in opposite directions, so that the water that flows down into the threads of the external screw generates a greater moment than that which rises in the threads of the internal screw, thus forming a closed hydraulic circuit capable of rotating continuously. Leonardo links two piston pumps to this device through a crankshaft, using the scroll system as a motor. This sheet is the last in a series of eight double sheets that formed an independent notebook on the theme of hydraulic machines based on the Archimedean screw. The notebook is viewed as an important step in Leonardo’s research towards his demonstration of the impossibility of perpetual motion both by Marcolongo, who considers it an error of his youth, and by Marinoni, who sees it as part of a study on perpetual motion that he would develop in the 1490s.