George Bidder, a mental calculator, aged twelve. Line engraving by S. Springsguth, 1818.

The sitter was from a poor background and uneducated; upon discovering his mental attribute his father exhibited him all over the country until he was fifteen. At this point Sir Henry Jardine raised funds for his education and in 1819 he entered the University of Edinburgh; here he became friends with Robert Stephenson, and went on to become a great engineer and entrepreneur. See Steven B. Smith, 'The great mental calculators', pp 211-220, 1983.