This machine accomplishes that which has heretofore been done by hand labor, viz., the separation of slate from coal. The slotted cylinder allows the oblong pieces of slate to escape; the beveled ribs insure the escape of the same, by preventing their motion, and causing them to assume a vertical position ; and the checkered grating allows the slated coal to escape, without any slate whatever passing off with it. It is the invention of Jacob Gass, of Trevorton, Pa.