He devoted time to studies in law and history , and in 1874 he succeeded Cosmo Innes as professor of constitutional law and history in the University of Edinburgh .
Mackay was admitted advocate at the Scottish bar in 1864 , and attained repute in consultation .
Mackay devoted time to studies in law and history , and in 1874 Mackay succeeded Cosmo Innes as professor of constitutional law and history in the University of Edinburgh .
Mackay was admitted advocate at the Scottish bar in 1864 , and attained repute in consultation .