Eustachio Porcellotti (19th century)
Galileo's pendulum clock, Florence, 1879
Florence, Istituto e Museo di Storia della Scienza, inv. 3450

To determine longitude at sea, Galileo designed in 1637 a time measurer regulated by a pendulum, in order to achieve a higher level of precision. This concept was based on the principle of the isochronous oscillations of a pendulum that he had discovered in his youth. The model illustrates Galileo's pendulum escapement idea.