Engraving by J Pas of a polygraph; apparatus for producing a simultaneous copy of a drawing or document. Its inventor, John Isaac Hawkins, received an American patent for it in 1803. A polygraph in modern usage means a device for recording physiological characteristics for use in lie detection. Illustration from 'Encyclopaedia Londinensis, or, Universal Dictionary of Arts, Sciences, and Literature' published in London, 1810-1829.
© Science Museum / Science & Society Picture Library