James David Forbes (20.04.1809-31.12.1868) was a Scottish physicist and a Fellow of the Royal Society of Edinburgh (1829), and its secretary in 1840 — 51. He was born in Edinburgh. He graduated from the University of Edinburgh, where he was professor in 1833 —59, and from 1859 he was principal of the University of St Andrews.
His work concerned heat, thermal radiation, electricity, optics and the study of glaciers. He discovered (1834) the polarisation of heat rays and observed their interference. He studied the thermal conductivity and electrical conductivity of bodies, in particular the thermal conductivity of metals. He was the first to demonstrate the dependence of thermal conductivity on temperature.
He was a Fellow of the Royal Society (1832) and a member of the Paris Academy of Sciences (1842). The B. Rumford Medal and the Royal Medal.