A short dictionary entry from Knight's American Mechanical Dictionary describing the hat-ironing machine, which mechanized the final hand-ironing step in finishing a hat. It explains how a rotating block holds the hat while hollow irons, heated by gas jets, steam, hot air or heated slugs, are pressed against it by weights or springs. It also covers finishing the under brim, and includes a cross-sectional drawing (Fig. 2434) of a machine with a turn-table, pendent irons, levers and counterweights.