The square of cloth on the back of sailor's uniforms comes from traditional sailor tops when sailors tied back their long hair, braided it and dipped it in tar. They wore kerchiefs (cut from old sails) tied around their necks to protect their clothes or backs when they were shirtless. And the larger cuffs (bell bottoms) were so they could get their britches on or off over their shoes. Speaking of pants and sails, during the 1849 California gold rush, Levi Strauss knew there was a market for durable clothes for the prospectors. At the time so many people were heading to California's gold fields that the ships they were taking west would often be abandoned- the crews often going out to stake claims. As a result canvas sail cloth was readily available. Strauss decided to make durable pants from this canvas, using rivets on the stress points. At some point the canvas was dyed using indigo. And the Levi Strauss Blue Jean Company was formed. The abandoned ships were often used for various businesses, not all of them strictly legitimate (bars, gambling dens, opium dens, brothels). Even today when construction is going on close to the modern waterfront they'll find one of these old ships.