'Haagsche Klokje', pendulum clock, c 1657.

View of pendulum. This clock by Salomon Coster (d 1659) of the Netherlands is one of the earliest pendulum clocks ever made. The Dutch scientist Christiaan Huygens (1629-1693) designed the first succesful pendulum clock in 1656. He worked with Coster, an experienced clockmaker, to apply his new invention to commercial use. In 1857 Huygens had the patent protecting his invention asigned to Coster, but sadly Coster died suddenly in 1659 after producing only a few pendulum clocks. This is one of only seven pendulum clocks made by Coster known to have survived. The application of the pendulum to clock timekeeping during the scientific revolution of the 17th century was arguably the most fundamental advance in the history of time measurement.