Drawings by Leonardo Da Vinici on on the mechanical powers and forces; percussion; gravity; motion; optics and astronomy; with various arithmetical and geometrical propositions. Written backwards in the author's own hand; and illustrated by diagrams and delineations. Leonardo Da Vinci's rough Book of observations and demonstrations on subjects chiefly of mixed Mathematics. being unconnected notes written by him at different times; commencing 22 March; 1508.Italy; early 16th century.From: Leonardo Da Vinci's rough Book of observations - equestrian portrait.Arundel 263 ff. 264v; 269London; British Library.