Martin's Improved Sphygmomanometer in its case, dating from 1920. This instrument is made in glass and mercury by S. Maw, Son and Sons. The sphygmomanometer was originally invented by Samuel Siegfried Karl Ritter von Basch in 1881. It was used to measure blood pressure; the cuff (brown) would be placed around the patient's arm whilst the physician placed their finger on the wrist to feel for the radial pulse. The cuff was inflated using the rubber bulb (black) until the pulse could no longer be felt. The level of the mercury in the glass tube (which would be placed vertically) would indicate the pressure in the cuff. The pressure would be released from the cuff slowly and the point at which the radial pulse returned would be read from the level of the