For more than a hundred years the Harlinger family Ratsma were the town's carilloneurs - they determined the daily rhythm in the town. They were also clockmakers and  they had so much craftsmanship, knowledge and insight that they were able to make complex clockworks. Some clocks not only indicated the time but also the day, the month and the year as well as the position of the sun, the moon and the planets.

In the museum the oldest 'horlogerie' is also the most special. At the top of the clockface there is a 'planisferium': a kind of disc on which the celestial map is portrayed. You will have to stretch to see the stars however, even indoors they are high in the heavens with such a tall clock! The clock also contains a chiming mechanism which plays twelve melodies including a free interpretation of the Dutch National Anthem, known as the Wilhelmus.