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German, Syriac, Arabic, Sanscrit, Hindu- stani, and Malay, and had written a letter in Persian to the Persian ambassador on his visiting Dublin. In mathematics he was almost self-taught. Entering Trinity College in 1822, he carried every- thing before him, and had mastered Newton's Primipia, the DiflFerential .Cal- culus, and La Place's Mecanique Celeste before he was nineteen. A paper contain- ing original researches on curves of double curvature, and a memoir on caustic curves, read before the Eoyal Irish Academy in 1824, placed him in the front rank of scien- tific Irishmen. The astronomers of Europe were somewhat astonished when, in 1827, a young man who had not attained the age of twenty-two stepped at once from the position of an undergraduate to that of Andrews Professor of Astronomy and superintendent of the Observatory at Dunsink, near Dublin, especially as he was not known to have displayed any talent for practical astronomy or observ- ing. Until his marriage in 1833, tis sisters, women of uncommon abilities, resided with him at the Observatory, Dunsink. He early produced his great work on The Theory of Systems of Rays, " which with its supplements is regarded as of the high- est importance in relation to the geometry of optics. Chasles spoke of it as ' dominant toute cette vaste theorie.' Starting from the fundamental idea that light, whatever be its cause or constitution, must be amenable to the principle of least action (nature's economy in using up force), he arrived at most important deductions relating to re- flection and refraction. One of his disco- veries, literally made upon paper, was that of conical refraction, a thing neither known nor surmised by practical experimenters in optics." *> This discovery was first veri- fied experimentally by Eev. Humphrey Lloyd. Mr. Hamilton was knighted by Lord Mulgravein 1835, on the occasion of the first meeting in Dublin of the British Association. In 1837 he was elected Pre- sident of the Koyal Irish Academy; of which, from 1832, he was one of the most active members. His works on General System of Dynamics, Calculus of Quater- nions, and his various contributions to philosophical transactions, besides stores of mathematical research left behind in MS., and to which it has been said the scientific world has not yet come up, are all monuments of his amazing genius and abili- ties. His Calculus is considered by mathe- maticians to be of great scope and power ; it has been illustrated and developed since his death by Professor Tait of Edinburgh. He declined becoming a member of the

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Eoyal Society on account of some conditions incident to membership. Poetry had a great charm for him — he numbered amongst his friends Coleridge, Southey, Wordsworth, and Mrs. Hemans, while his own poetical productions are of some value, "more, perhaps, as beautiful emanations of his character, evidencing the strength and gene- rousness of his affections, and the loftiness of the aspirations and communings of his spirit, than as works of poetic art." '"^ A beautiful ode commencing " brooding spirit of wisdom and of love " is given in his memoir in the Dublin University Magazine. He had little love of money, and was content to spend his days in the Obser- vatory at Dunsink, on a small salary. He appeared last in public at the Dublin Exhibition of 1865, and died the 2nd of September in the same year, aged 60. His sister Elizabeth Mary in 1838 pub- lished a volume of poems dedicated to him. 40 116(19) 233

Hand, Edward, Brigadier-General, United States Army, was born at Clyduff, in the King's County, 31st December 1744. In October 1774 he accompanied the i8th Eoyal Irish to America, as surgeon's mate ; he resigned his post on arrival, and settled in Philadelphia for the practice of his pro- fession. He espoused the cause of the Eevolution, joined a rifle regiment as Lieu- tenant-Colonel, and served at the siege of Boston. In March 1776 he was promoted to be Colonel, and led his regiment at the battles of Long Island and Trenton. As Brigadier-General he was in command at Albany in October 1778, and soon after- wards was engaged in Sullivan's expedition against the Indians of central New York. He held other important commands during the war, and after its termination was a member of the old Congress, i784-'5 ; and his name is affixed to the Pennsylvania constitution of 1790. In 1798, when Washington accepted the command of the army raised in anticipation of a war with France, he recommended the appointment of Hand as Adjutant-General. He died at Eockford, Lancaster County, Pennsyl- vania, 3rd September 1802, aged 57. ^*

Hanger, George, Lord Coleraine, better known as Colonel Hanger, born in Ireland about 1 750, was distinguished alike by his talents and his eccentricities. He entered the army at an early age, and served in America during the whole of the war of independence. The highest rank he reach- ed was that of Major of the British Legion of Cavalry. In 1789 he published A n Ad- dress to the Army relative to the Campaigns 0/ 1 780 and '81. He mixed much in fash- ionable society, where he was always wel- 243