A mechanism by Dudgeon which recorded the pulse pressure and rhythm at the wrist. He presented this instrument in 1881. This example was made by Maw Son & Thompson who were in business until 1901.
A sensitive manometer sits on the radial pulse and is amplified by means of a weighted pulley. A clockwork mechanism turns a roller which winds recording paper under the needle to record a trace. Dudgeons device largely replaced Marey’s instrument in popularity because of the relative ease of use and its diminutive size which allowed it to be carried in a pocket. It tended to be the remit of physiologists rather than doctors who were encouraged to rely more on their “finger” (clinical skills) although it was certainly used by many physicians and cardiologists. A fascinating precursor to the ECG / sphygmomanometer which remarkably remains in good working order.
Ext Link: The Dudgeon sphygmograph and its descendants (PDF)