A short dictionary entry on the hat-napping machine, reproduced from Knight's American Mechanical Dictionary. It explains that a felted hat body is dipped in boiling water and its nap raised with a small hand-card, a process also called ruffing, and cites an 1837 English patent. A line drawing (Fig. 2436) shows a hat mold on a base with a lever press, hand crank wheel and water valve.