Joseph Black, the discoverer of "fixed air" (carbon dioxide), was appointed to the Chair of Medicine and Chemistry at the University of Edinburgh in 1766. He was the tutor in chemistry and conducted a popular course of lectures in chemistry until he retired in 1796. [1] Black had earned renown for developing the theories of latent and specific heat. His course ran from mid-November until mid-May. 

Lord Cockburn, Lawyer and judge was a childhood neighbour who described Dr. Black in poetic terms, as follows: “He was a striking and beautiful person; tall, very thin, and cadaverously pale; his hair carefully powdered, though there was little of it except what was collected into a long thin queue; his eyes were dark, clear, and large, like deep pools of pure water. He wore black speckless clothes, silk stockings, silver buckles, and either a slim green silk umbrella, or a genteel brown cane. The general frame and air were feeble and slender.” He was a man “so pale, so gentle, so elegant, and so illustrious,” an “attenuated philosophical gentleman.” [2] 

At the time of his enrolment, William Symington was already employed as an assistant engineer to his brother George at Wanlockhead. Gilbert Meason, the managing partner of the Wanlockhead Mining Company, had encouraged William to pursue further education in the field of natural philosophy. A proficiency in the science of thermodynamics would have been highly advantageous, especially in relation to fundamental practical applications in steam engine design and construction.

In 1786, William and George had built a working model land carriage which was powered by a steam engine. The carriage was demonstrated at Leadhills and in Edinburgh. Black knew of the model but did not take the trouble to see it. In August 1786, Black wrote to James Watt "In the end of April last I had the pleasure to see two of your men very good like lads who had called on me at your desire. One of them talked a little of your haveing a Scheme among you for makeing waggons travel by means of your Engine. Are you serious in such a design? Some of Gilbt Measons men have been working at it and have made a small model but I have not such an opinion of their heads as to have much curiosity to see their model. it is reported they have taken a patent for it" [3] 

[1] Robison, John, Lectures on the elements of Chemistry delivered in the University of Edinburgh by the late Joseph Black John Nelson 1803

[2] Cockburn, Henry, Memorials of His Time. Edinburgh 1856, pages 50, 51

[3] Dickinson, Henry Winram, Some unpublished letters of James watt, Excerpt. Proc. Inst. Mech. Eng., pages 487-534