Measure of the Heart: Santorio Santorio and the Pulsilogium

In 1626, the Venetian physician Santorio Santorio published the details of his pulsilogium, a stop clock that could accurately measure one's pulse rate. He applied Galileo Galilei's insights that the frequency of a pendulum's oscillation is inversely proportional to the square root of its length. Santorio's inventions emerged at a time when the natural world and our solar system were beginning to be mapped in remarkable detail. Santorio was a true representative of his era, a period in which scientific developments came in rapid succession and measurements to support hypotheses became the norm.