Eli Whitney went down in history as the inventor of the cotton gin, a machine made to extract seeds from cotton, patented in 1794. Whitney spent a decade fighting patent infringements, and years of litigation left him nearly penniless by 1804. Whether he was the sole inventor of the gin is still a matter of debate, yet Whitney clearly had a knack for manufacturing and business: after the cotton gin he went into the firearms business, using his mechanical skills to design a system for manufacturing identical and interchangeable parts for rifles. He operated a successful firearms factory near New Haven, Connecticut until he retired around 1820.