A rare sphygmograph by Richardson which has an adjustable weight allowing pressure on the radial pulse to be varied.

One of the problems with the early sphygmographs was that they were fiddly to set up and it could be difficult to engage the manometer with the radial pulse. This instrument is very similar in design to the Dudgeon Sphygmograph with this extra feature which allowed the operator to increase the pressure over the artery in orer to record a measurement. It comes in a fitted silk and velvet lined leather case signed in the lid by the maker Ludwig Droll of Frankfurt.

• From the Phisick collection