Bark mill with pestles

This model, already in the museum’s collection at the beginning of the 19th century, perfectly illustrates the use of a natural energy source and the transmission of movement via a drive shaft powered by a waterwheel. From the 12th century, bark mills were used to grind oak bark into the powder, the tan (or tanbark), used for dyeing skins in tanneries. With this, skins could be transformed into rot-proof leather. The waterwheel’s drive shaft has cams, which in turn raise each of the six pestles, which fall under their own weight to break the bark.