John Southern (engineer)

[1] In 1796 he and his employer James Watt co-invented the Indicator, an instrument for measuring and recording the pressure inside a steam engine cylinder through its stroke.

[2] This data was crucial for assessing an engine's efficiency.

Southern became a partner of the firm of Boulton & Watt in 1810.

[1] The use of the instrument was kept as a trade secret for a generation, only becoming public in the 1830s.

This article about an engineer, inventor or industrial designer from England is a stub.