A short dictionary entry from Knight's American Mechanical Dictionary describing the hat-brim trimmer, a pattern or device that fixes where a hat brim is cut. It explains the rounding-jack, a curved knife with a gage that bears against the band point while the hat is on the block, so the brim is cut to an equal width all round. One cross-section line drawing (Fig. 2427) shows the hat on a block with the knife and gage mechanism.