William Harvey was an English physician who made seminal contributions in anatomy and physiology. He was the first known to describe completely and in detail the systemic circulation and properties of blood being pumped to the brain and body by the heart, though earlier writers, such as Miguel Servet (aka Michael Servetus, Michel de Villeneuve) in: ‘Restitutio Christianismi’, Paris, 1546, and Jacques Dubois, had provided precursors of the theory.

Born: April 1, 1578, Folkestone, United Kingdom

Died: June 3, 1657, Roehampton, London, United Kingdom

Education: University of Cambridge, Gonville and Caius College, Cambridge, University of Padua

Harvey earned around thirty-three pounds a year and lived in a small house in Ludgate, although two houses in West Smithfield were attached as fringe benefits to the post of Physician. At this point, the physician’s function consisted of a simple but thorough analysis of patients who were brought to the hospital once a week and the consequent writing of prescriptions.

“…I found the task so truly arduous… that I was almost tempted to think… that the movement of the heart was only to be comprehended by God. For I could neither rightly perceive at first when the systole and when the diastole took place by reason of the rapidity of the movement…”

He estimated that the capacity of the heart was 1.5 imperial fluid ounces (43 ml), and that every time the heart pumps, 1/8 of that blood is expelled. This led to Harvey’s estimate that about 1⁄6 imperial fluid ounce (4.7 ml) of blood went through the heart every time it pumped. The next estimate he used was that the heart beats 1000 times every half an hour, which gave 10 pounds 6 ounces of blood in a half an hour, and when this number was multiplied by 48 half hours in a day he realized that the liver would have to produce 540 pounds of blood in a day.