An International Correspondence Schools instruction paper (Serial 495) on dobby shedding mechanisms for power looms. It describes open, close, split and compound sheds, then the construction, drive and operation of single-cylinder dobbies and their variations (positive/non-positive, single- and double-lift, single- and double-index, pawl-and-ratchet drive, right- and left-hand). It also covers the double-cylinder dobby with repeat motion, building and pegging harness chains, and timing, setting, skipping faults, and power and speed.