Oldest pendulum clock

The oldest surviving example of a pendulum clock is the 1657 Hague Pendulum Clock, made by Salomon Coster, which is in the collection of the Rijksmuseum Boerhaave in Leiden, Netherlands. The clock face is inscribed "Salomon Coster. Haghe. met privilege 1657", which translates as "Salomon Coster, Hague. With Permission, 1657". The last part is a reference to Coster having purchased the rights to the pendulum clock design from its inventor, Dutch scientist Christiaan Huygens. At the time this clock was made, the invention was less than a year old, and Huygens hadn't yet published his book, Horologicum, in which the principles were explained.