James David Forbes FRS FRSE FGS (1809–1868)[1] was a Scottish physicist and glaciologist who worked extensively on the conduction of heat and seismology.

Forbes was a resident of Edinburgh for most of his life, educated at its University and a professor there from 1833 until he became principal of the United College of St Andrews in 1859.

In 1859 he was appointed successor to Brewster in the principalship of the United College of St Andrews, a position which he held until his death at Clifton in 1868.

[7] In 1846 he began experiments on the temperature of the earth at different depths and in different soils near Edinburgh, which yielded determinations of the thermal conductivity of trap-tufa, sandstone and pure loose sand.

[8] His attention was directed to the question of the flow of glaciers in 1840 when he met Louis Agassiz at the Glasgow meeting of the British Association, and in subsequent years he made several visits to Switzerland, where he was particularly impressed by Bernhard Studer's theories,[9] and also to Norway for the purpose of obtaining accurate data.

His observations led him to the view that a glacier is an imperfect fluid or a viscous body which is urged down slopes of a certain inclination by the mutual pressure of its parts, and involved him in some controversy with Tyndall and others both as to priority and to scientific principle.

The grave is marked by a simple but large grey granite Celtic cross and lies on the south side of the main path just west of the roundel.