Sphygmograph

The device was a system of levers hooked to a scale-pan in which weights were placed to determine the amount of external pressure needed to stop blood flow in the radial artery.

Although the instrument was cumbersome and its measurements imprecise, the basic concept of Vierordt's sphygmograph eventually led to the blood pressure cuff used today.

Also he included a specialized instrument to be placed above the radial artery that was able to magnify pulse waves and record them on paper with an attached pen.

This modified version made the sphygmograph quantitative, so that it was able to measure arterial blood pressure.

In 1901 Harvey Williams Cushing improved it further, and Heinrich von Recklinghausen (1867–1942) used a wider cuff, and so it became the first accurate and practical instrument for measuring blood pressure.