Christiaan Huygens, Dutch physicist, 1660s.
© Science Museum / Science & Society Picture Library
Portrait medallion. Christiaan Huygens (1629-1693) was responsible for two great advances in horology: the application of both the pendulum to the clock and the balance spring to the watch. The clockmaker Salomon Coster of the Hague made his first pendulum clock, and a patent was isued in Coster's name in 1657. Although Galileo Galilei (1564-1642) had suggested the use of a pendulum to count the time, Huygen's design, where the clock's dial and hands are controlled by a pendulum, was the first truly practical pendulum clock.