Hindley's pyrometer with three expansion tubes, 1752.
© Science Museum / Science & Society Picture Library
The famous 18th century science lecturer Dr Stephen Demainbray used this instrument to measure the expansion of various types of metal when heated. The metal bar to be tested was fitted acros the base and was heated by a series of wicks floating in oil. The expansion of the metal moved the pointer round the dial. Henry Hindley, who designed it, was a well-known instrument maker from York.