English: The front (or obverse or face) of a 1779 fifty-five dollar bill of Continental currency. On the other side of the bill is a nature print that was developed by Benjamin Franklin for use on Pennsylvania currency in the decades before the American Revolution. Since no two leaves are alike, it was hoped that the design would aid in detecting counterfeit bills. Franklin's specific method for making these was kept a secret and is unknown, but this form of nature printing was prevalent in the American colonies and the United States from the 1730s through 1779, when Delaware, Maryland, Pennsylvania, and New Jersey issued nature-printed currency. After Franklin retired from printing, his partner David Hall formed the firm of Hall & Sellers, which (after Hall's death) used Franklin's technique on Continental bills like this one. For more info, see http://www.coins.nd.edu/ColCurrency/CurrencyText/CC-01-14-79b.html , http://www.coins.nd.edu/ColCurrency/FAQ/cc-notesinfo.html , and https://www.loc.gov/exhibits/franklin/franklin-printer.html . From a private collection, exhibited at Glyndor Gallery, Wave Hill, The Bronx, New York.