It is based on instructions published by R. Beijersbergen van Henegouwen (200-2004) It has been modified slightly to ensure that it works reliably. The output shaft is journaled in one of the slotted holes of the 1½" Flat Girder which are backed by 2 fishplates. This allows its position to be adjusted. It has been built into a small model of a Windmill which has survived much vigorous use by young visitors to exhibitions.