Raftsman Martin Spang from the Upper Nagold Valley Raftsmen's Guild at the Monhardter Wasserstube. It served as a dam to assist the raftsmen in floating timber. Streams were dammed to provide enough water to transport large quantities of timber from the Black Forest to distant areas on rafts. This mechanism was a central component of rafting, which was an important industry in the Black Forest for almost 500 years. Raftsman Martin Spreng. Altensteig, Baden-Württemberg, Germany