What occupation did both William Sellers and Joseph Whitworth have?
William Sellers: William Sellers (September 19, 1824 – January 24, 1905) was a mechanical engineer, manufacturer, businessperson, and inventor who filed more than 90 patents, most notably the design for the United States standard screw thread. Joseph Whitworth: Sir Joseph Whitworth, 1st Baronet (21 December 1803 – 22 January 1887) was an English engineer, entrepreneur, inventor and philanthropist.
engineer