Jean Léonard Marie Poiseuille (22 April 1797 – 26 December 1869) was a French physicist and physiologist.

Life

Poiseuille was born and died in Paris. From 1815 to 1816, he studied at the École Polytechnique in Paris, where he learned about physics and mathematics. In 1828, he received his D.Sc. degree for a paper titled Recherches sur la force du coeur aortique (The force of the aortic heart). He studied how human blood flows through narrow tubes and created the U-tube mercury manometer (or hemodynamometer) to measure blood pressure in horses and dogs.

In 1838, he discovered through experiments and later published a rule now called Poiseuille’s law (also known as the Hagen–Poiseuille equation, which credits Gotthilf Hagen). This law explains how liquids flow smoothly, not in a turbulent way, through pipes with the same width, such as blood moving through capillaries and veins. The unit of viscosity in the CGS system, called the poise, was named after him. A proposed SI unit for viscosity, the poiseuille, was also named in his honor.