John W. Nystrom
John Williams Nystrom () (1825–1885) was a Swedish born, American civil engineer, inventor, and author. He served as an assistant Secretary and Chief Engineer of the United States Navy during the American Civil War. Background. He was born Johan Vilhelm Nyström in Småland province, Sweden. He received his engineering degree from the Royal Institute of Technology ("Kungliga Tekniska högskolan") in Stockholm, Sweden. He emigrated to the United States in the 1840s, and became an American citizen in 1854. He maintained residence in Philadelphia, Pennsylvania, where he died on May 11, 1885. Inventions and patents. Nystrom received many patents  for inventions such as a marine steam engine, a refrigerator, and calculating machines. His slide ruler invention (U. S. patent #7961) was filed with the United States Patent Office on 4 March 1851. Nystrom is most notable for his proposal to switch from decimal to hexadecimal as defined in his 1862 publication titled "Project of a New System of Arithmetic, Weight, Measure and Coins, Proposed to be Called the Tonal System, with Sixteen to the Base". Numeral systems. Tonal system (hexadecimal). In 1859, Nystrom proposed a hexadecimal (base 16) system of notation, arithmetic, and metrology called the Tonal system. In  addition to new weights and measures, his proposal included a new calendar with sixteen months, a new system of coinage, and a hexadecimal clock with sixteen hours in a day. Duodenal system (duodecimal). In 1875, Nystrom proposed a new duodecimal (base 12) system of notation, arithmetic, and metrology called the Duodenal system as an appendix in his book "A New Treatise on Elements of Mechanics Establishing Strict Precision in the Meaning of Dynamical Terms".