James MacCullagh (1809-24.10.1847) was an Irish theoretical physicist and a member of the Royal Irish Academy (1833). He was born near Strabane. He graduated from Trinity College in Dublin, where in 1833 he became professor of mathematics and in 1842 professor of natural philosophy.
His main work was in the field of mathematical physics, optics and electricity. In 1839 he constructed the theory of an incompressible ether (MacCullagh's dynamical theory).
The Copley Medal (1842).