James McCullagh

McCullagh, James, one of the most eminent mathematicians of his day, the son of a blacksmith, was born at Landahussy, in the County of Tyrone, in 1809. He entered Trinity College as a sizar in 1824; in 1827 was elected a scholar, and in 1832 obtained a fellowship. He early became a member of the Royal Irish Academy and an important contributor to its proceedings: from 1844 to 1846 he was its Secretary, and he did much to raise its status: he presented the Cross of Cong and other antiquities to the museum. He was the author of valuable papers on light and refraction. In 1838 he gained the Academy's medal for an essay on "Laws of Crystalline Reflection and Refraction," in which "he linked together, by a single and simple mathematical hypothesis, the peculiar unique laws which govern the motion of light in its propagation through quartz."[39]

In 1846 the Royal Society awarded him the Copley medal for like researches. His lectures as Professor of Natural Philosophy in the University of Dublin are said to have given an impetus to the study of the more abstruse sciences. "It was in the delivery of them that Professor McCullagh used to display the extensive information, the elaborate research, and the vast acquired treasures of his highly cultivated mind... Nothing could exceed the depth, or surpass the exquisite taste and elegance of all his original conceptions, both in analysis and in the ancient geometry in which he delighted... In his investigations on the dynamical theory of light — the unaided creation of his own surpassing genius — he has reared the noblest fabric which has ever adorned the domains of physical science, Newton's System of the Universe alone excepted."[39] This is doubtless an over estimate of the value of his researches.

In private life he was retiring, modest, and unselfish. To his public spirit was in a measure due the break-up of the practice of choosing the parliamentary representatives of the University from men educated outside its precincts. Towards the end of 1847 the confinement and intense application consequent on researches connected with a paper on A Theory of the Total Reflection of Light, brought on dyspepsia and melancholia; his mind was overturned, and he died by his own hand in his college chambers, 24th October, aged about 38. His remains were interred near Strabane.


16. Authors, Dictionary of British and American: S. Austin Allibone. 3 vols. Philadelphia, 1859-'71.

39. Biographical Dictionary, Imperial: Edited by John F. Waller. 3 vols. London, N.D.

146. Gentleman's Magazine. London, 1731-1868.
Gilbert, John T., see Nos. 110, 335.