The Double Reduction Grinding Disc.

The first reduction is
produced in the bosomed
part of the disc where the furrows run, sharp cutting edge front, to cut the grain fine with least power possible.
The second reduction is produced upon the flat outer circle of furrows, running their incline sides front, to mash and mellow the meal already
cut fine. The saw-toothed inner edge of the discs form a natural crusher,

to reduce pieces of cob so as to pass through the mill by aid of the conveyor-flights, which are arranged around the eye of the discs. They also draw in the air and pass it through to cool the meal whilst grinding.

This cut, showing enlarged section of grinding disc, more perfectly
illustrates the arrangement of the conveyor-flights upon the saw-
toothed inner edge; they act like a fan, to draw cool air and grain into
the mill while running at a very low speed: The grain, first cut fine, is
then rolled, mashed and mellowed so perfectly that it enlarges nearly
one-third in bulk.