Dr William Cullen (1710-1790) was a leading physician of the Enlightenment era. As professor in Edinburgh he became the most influential teacher of theoretical and practical medicine in 18th century Britain. A renowned private practitioner, Cullen systematically archived his postal 'consultations', now held by the Royal College of Physicians of Edinburgh. Initially Cullen preserved his replies as transcriptions, but from April 1781 he began using a mechanical copier, newly devised by the Scottish engineer James Watt. This paper describes the development, promotion and functioning of Watt's copier and considers Cullen's own adoption of the machine. It is suggested that with Cullen's adoption of Watt's copier, medical record keeping entered a new historical phase comparable with the recent digital revolution.