In 1733, Stephen Hales of the Royal Society of the United Kingdom conducted blood pressure measurements for the first time, but at the time there was no mercury blood pressure meter we used now. The method used was to use a thin copper tube with one sharpened tip and one connected. Into a long glass tube.
Then the sharpened head is inserted into the carotid artery, and blood is poured into the glass tube. As the heart beats, the height of the blood column in the glass tube also changes up and down. This is the first time in the history of blood pressure measurement test.
Of course, the test object is a horse. Although this blood pressure measurement method cannot be applied to people, it also allows humans to visually recognize the physiological phenomenon of blood pressure for the first time.