A late 19th-century sphygmometer for measuring blood pressure by le célèbre fabricant d’instruments Français, Charles Verdin.

This blood pressure device consists of a small cylinder containing a coiled spring, activated by a central rod that terminates to a perpendicular surface. Placing the palpating finger on the radial pulse, the distal end of the instrument is pressed into the fingernail until the pulse is no longer felt beneath the stationary digit. The blood pressure is then revealed on a telescoping scale, measured in centimètres de mercure.

As an indicator of the condition of the vascular system, this instrument only provided absolute blood pressure measurement without diastolic calculation, and readings were subject to inaccuracy due to inconsistent technique and varied anatomical makeup.

• From the Lusignan collection