# 1911 Encyclopædia Britannica/MacCullagh, James

**MACCULLAGH, JAMES** (1809–1847), Irish mathematician
and physicist, was born in 1809, near Strabane, Ireland. After
a brilliant career at Trinity College, Dublin, he was elected
fellow in 1832. From 1832 to 1843 he held the chair of mathematics;
and during his tenure of this post he improved in a
most marked manner the position of his university as a mathematical
centre. In 1843 he was transferred to the chair of
natural philosophy. Overwork, mainly on subjects beyond
the natural range of his powers, induced mental disease; and
he died by his own hand in October 1847.

His *Works* were published in 1880. Their distinguishing feature
is the geometry—which has rarely been applied either to pure space
problems or to known physical questions such as the rotation of a
rigid solid or the properties of Fresnel’s wave-surface with such
singular elegance; in this respect his work takes rank with that of
Louis Poinsot. One specially remarkable geometrical discovery of
MacCullagh’s is that of the “modular generation of surfaces of the
second degree”; and a noteworthy contribution to physical optics
is his “theorem of the polar plane.” But his methods, which, in
less known subjects, were almost entirely tentative, were altogether
inadequate to the solution of the more profound physical problems
to which his attention was mainly devoted, such as the theory of
double refraction, &c. See G. G. Stokes’s “Report on Double
Refraction” (*B. A. Report*, 1862).