The "Westermolen" ("molen" means "mill") is a wip water mill. This type of mill evolved from the post mill. The rectangular mill house; is quite noticable.
You can much more about a wip mill and other types of windmills on this website :
Here is another windmill that I saw on my way to the Kinderdijk; The "Boterslootse molen" in Noordeloos. This is also a wip water mill just like the "Westermolen"
The mill was build in 1837 on the same spot where in that same year a mill burnt down because it was hit by lightening. In 1956 went out of use. In 1991 the mill was completely restored.
Water mill and windmill :
There are two distinctive types of mills in the Dutch countryside, the water mill and the windmill.
The water mill can be found in eastern and southern regions of Holland: Twente (see my Denekamp page), Oost-Veluwe, the Achterhoek, Oost-Brabant, and Limburg. In these places there was a sufficient flow of water to drive the wheel of the mill. The water mills were usually used as corn mills, but they also produced paper, oil and sawed timber. There are approximately 70 of this type left in Holland.
The windmill is divided into two categories, the industrial mill and the drainage mill.
The industrial mills were named according to their use, sawmill, etc., but have succumbed to modern technology (there are still a few left). The drainage mills keep the land behind the dikes free of surplus water, thereby creating "polders" (reclaimed land). These mills are still functioning in some of the older polders. The sails of the mill catch the wind, which in return moves the millstones. There are approximately 1,000 windmills left and they can be found dispersed throughout 12 provinces, but mostly in Zuid Holland.