Singer had seen a rotary sewing machine being repaired in a Boston shop. As an engineer, he thought it was clumsy and decided to design a better one. The machine he devised used a falling shuttle instead of a rotary one; the needle was mounted vertically and included a presser foot to hold the cloth in place. It had a fixed arm to hold the needle and included a basic tension system. This machine combined elements of Thimonnier, Hunt and Howe's machines. Singer was granted an American patent in 1851. The foot treadle used since the Middle Ages, used to convert reciprocating to rotary motion, was adapted to drive the sewing machine, leaving both hands free.