US250564A Roller grindingmill Google Patents
US250564A US250564DA US250564A US 250564 A US250564 A US 250564A US 250564D A US250564D A US 250564DA US 250564 A US250564 A US 250564A Authority US United States Prior art keywords rollers roller mill depressions roller grinding Prior art date Legal status (The legal status is an assumption and is not a legal conclusion.