Cartier is widely credited with having created the wristwatch in 1904, essentially as a custom order for Brazilian aviator Alberto Santos-Dumont. A friend of Louis Cartier, Santos-Dumont wanted to have a watch attached to his wrist while flying so he could easily glance at what was then the only navigational instrument for pilots, amateurs and professionals alike. Others used pocket watches, which they had to yank out of their pockets to check their progress. Some strapped pocket watches to their legs, which strikes me as an odd alternative to the pocket, and others simple attached their watches somehow to the control panel. The early Santos pictured here is yellow gold, with the signature Cartier railroad track index and Roman numerals still used today, as well as a sapphire cabochon crown. It is the ultimate classic.