The Italian polymath Leonardo da Vinci drew his design for an "aerial screw" in the late 1480s, while he was employed as a military engineer by Ludovico Sforza, Duke of Milan from 1494 to 1499. The original drawing is part of a manuscript dated to 1487 to 1490 and appears on folio 83-verso of Paris Manuscript B, part of the papers removed from the Biblioteca Ambrosiana in 1795 by Napoleon and still held by the Institut de France in Paris.