An International Correspondence Schools instruction paper on drop-box motions for power box looms, which carry several shuttles of different filling colors. It describes the Crompton 4x1 box motion in detail: picker connection, lifting lever, star gear, front and back shafts, box chain, multiplier motion and still box motion. It also explains how to build box chains from a filling draft and how to time, level and adjust box looms, and closes with power and speed figures. Illustrated with mechanical line drawings and one box-chain draft.