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Dudgeon sphygmograph shown in the position for use. It is made out of nickel and dates from the 1880s, England. The sphygmograph, originally invented in 1854 by German physiologist Karl von Vierordt, was used by physicians in the mid-nineteenth century as a means of observing and measuring the pulse externally and non-invasively. The radial pulse wave forms would be traced with a mounted pen using a clockwork mechanism. This design was invented by Robert Ellis Dudgeon (1820-1904), an Edinburgh-trained doctor who later became a homeopath. Dudgeon's sphygmograph replaced the earlier design by E.J. Marey which was heavier and less portable.
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