William S. Burroughs (1857-1898), of St. Louis,  got his idea of building a calculator while working with Frank Stephen Baldwin, another inventor of calculating machines.  He patents an adding machine. He started the construction in 1882; he resigned from a bank were he worked at that time in order to be able to fully dedicate his time towards the development of the adding machine. He invents a machine similar to Felt's but more robust, and this is the one that really starts the office calculator industry.
 
Burroughs receives his first patent in 1888 and had manufactured 50 machines by the next year.  The machines were recalled and soon afterwards Burroughs invented a corrective automatic device.