John Southern (engineer)


John Southern (c.1758–1815) was an English engineer, son of Thomas Southern of Derbyshire.[1] He co-invented the indicator diagram with his employer, James Watt, in 1796.[2] Southern became a partner of the firm of Boulton & Watt in 1810.[1] The use of the diagram was kept as a trade secret for a generation, only becoming public in the 1830s.[3]

A Treatise upon Aerostatic Machines, 1785, by John Southern


  1. ^ a b H. W. Dickinson (31 October 2010). James Watt: Craftsman and Engineer. Cambridge University Press. pp. 131–. ISBN 978-1-108-01223-2.
  2. ^ Baird, Davis (2004). Thing knowledge: a philosophy of scientific instruments. University of California Press. p. 170. ISBN 978-0-520-23249-5.
  3. ^ M. Norton Wise (March 1997). The Values of Precision. Princeton University Press. p. 231. ISBN 0-691-01601-1.