Excerpt from The Private Life of Galileo By Galileo Galilei, Maria Celeste Galilei, Mary Allan-Olney

Galileo and the Cathedral Lamp

The connection of the great bronze lamp in the nave of the cathedral at Pisa with Galileo's earliest mechanical discovery is well known. Viviani says that having observed the unerring regularity of the oscillations of this lamp and of other swinging bodies the idea occurred to him that an instrument might be constructed on this principle which should mark with accuracy the rate and variation of the pulse. Such an instrument he constructed after a long series of careful experiments This invention though imperfect was hailed with wonder and delight by the physicians of the day and was soon taken into general use under the name of pulsilogia.