John Southern (c.1758–1815) was an English engineer, son of Thomas Southern of Derbyshire. He co-invented the indicator diagram with his employer,

James Watt James Watt (; 30 January 1736 (19 January 1736 Old Style and New Style dates, OS) – 25 August 1819) was a Scottish people, Scottish invention, inventor, mechanical engineer, and chemist who improved on Thomas Newcomen's 1712 Newcomen steam ...

, in 1796. Southern became a partner of the firm of Boulton & Watt in 1810. The use of the diagram was kept as a trade secret for a generation, only becoming public in the 1830s.

References

English engineers 18th-century British engineers People from Derbyshire 1815 deaths Year of birth unknown Year of birth uncertain {{England-engineer-stub