The sphygmograph was a mechanical device used to measure blood pressure in the mid-19th century. It was developed in 1854 by German physiologist Karl von Vierordt (1818-1884}. It is considered the first external, non-intrusive device used to estimate blood pressure.

An instrument which, when applied over an artery, indicates graphically the movements or character of the pulse. See Sphygmogram.