Physicist, born at Edinburgh, the grandson of Sir William, and the son of the first lady-love of Sir Walter Scott, and very like her; was called to the bar in 1830; physical science, however, was his ruling passion, and in 1833 he became professor of Natural Philosophy in Edinburgh University, from which he was called in 1859 to the Principalship of the United College, St. Andrews, in which he succeeded Sir David Brewster, whom he had defeated in obtaining the Edinburgh chair; he made some valuable contributions to natural science, including discoveries in the polarisation of heat and in regard to the motion of glaciers, to investigate which he travelled in Norway and in the Alps (1809-1868).