Hall, W. D. (1987). "Stephen Hales: theologian, botanist, physiologist, discoverer of hemodynamics". Clinical Cardiology. 10 (8): 487–9.
Reverend Stephen Hales was the first person to measure blood pressure. He did this in 1733 using a glass tube inserted in the carotid artery of a sedated horse. The artist chose to depict the tube coming out of the horse's neck but it was actually in the groin: “In December I caused a mare to be tied down alive on her back … having laid open the left crural artery about three inches from her belly, I inserted into a brass pipe whose bore was one-sixth of an inch in diameter and to that by means of another brass pipe which was fitly adapted to it, I fixed a glass tube of nearly the same diameter which was nine feet in length. Then , untying the ligature on the artery, the blood rose in the tube to eight feet in length, three inches perpendicular above the level of the left ventricle of the heart”.
8 feet 3 inches = 99 inches of blood = 185 mmHg blood pressure
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