Cog wheels (detail), late 15th or early 16th century (1954).Artist: Leonardo da Vinci [Getty Images]

Cog wheels (detail), late 15th or early 16th century (1954). Codex Atlanticus, 372r-b. A print from Leonardo da Vinci by Ludwig H Heydenreich, Macmillan, London, 1954. (Photo by The Print Collector/Print Collector/Getty Images)

Hulton Archive Print Collector