Galileo Galilei. Engraving of Galileo Galilei (1564-1642), Italian scientist, first noticing how a pendulum swings. While Galileo was a medical student in Pisa in 1582 he observed a lamp which was swinging in the city's cathedral, and so acting as a simple pendulum. He noticed that the lamp took the same time to do one swing, regard- less of how far it had to swing. This observation led him to perform experiments which showed that the period of a pendulum's swing depends on its length. He used pendulums to monitor a person's pulse rate and to regulate a clock. Galileo's lamp" which hangs in the cathedral was not installed until 1587 (and is now electric)."