A one-page dictionary entry on the hat-makers' battery, a large boiler surrounded by workbenches where fur napping is joined to a conical felt hat body. It explains the use of slightly acidulated hot water, the pressing, rubbing and rolling that felt the fur onto the body, and the wooden 'glove' used for rubbing. An engraving (Fig. 2435) shows workmen around the boiler with a hoist.