Bark mill
Bark mills, also known as Catskill's mills, are water, steam, horse, ox or wind-powered edge mills used to process the bark, roots, and branches of various tree species into a fine powder known as tanbark, used for tanning leather. This powdering allowed the tannin to be extracted more efficiently from its woody source material. A barker would strip the bark from trees so that it might be ground in such mills, and the dried bark was often stored in bark houses.