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Richardson's sphygmograph dating from around 1882. This sphygmograph is nickel and was made in England by Allen and Hanbury. The sphygmograph, originally invented in 1854 by German physiologist Karl von Vierordt, was used by physicians in the nineteenth century as a means of observing and measuring the pulse externally and non-invasively. A clockwork mechanism allows the radial pulse wave forms to be traced with a mounted pen.
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