The Royal College of Physicians of Edinburgh in cooperation with the University of Glasgow have made the entire collection of the consultation letters of renowned 18th century Edinburgh physician Dr. William Cullen available online. One such letter was written by Boswell requesting medical advice for his friend Dr. Johnson shortly before Johnson's death in 1784.
It has taken a massive effort to digitise and categorise William Cullen's letters. In all 5,603 documents have been made available comprising 20,678 pages. 3,799 of these documents have been fully transcribed and are now searchable. Cullen's archive is arguably one of the most important sources for the understanding of 18th century medicine. The letters are also complementary to those of Boswell as an invaluable source to life in Edinburgh ca 1760-1790.
The letter from Boswell concerning Dr. Johnson as well as Cullen's cautious reply is available here. Another letter relates to the final (fatal) illness of George Dempster's sister Margaret in 1764. The main site is available at www.cullenproject.ac.uk