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 thou hast missed”’ (Brit. Quart. Review, i. 197).

Like Newton and Buffon, Dalton disbelieved in what is called ‘genius,’ attributing its results to the determined pursuit of some one attainable object. The processes of his own mind were slow and difficult. He formed his ideas laboriously, and held them tenaciously. An extraordinary sagacity enabled him to reason accurately from frequently defective data. He was a coarse experimenter, and his apparatus (preserved by the Manchester Philosophical Society) was of the rudest and cheapest description. Yet his experiments were so carefully devised as usually to prove a guide to truth. As a teacher he was uncommunicative, as a writer dogged and matter-of-fact, as a lecturer ungainly and inelegant; his true greatness was as a philosophical investigator of the physical laws governing the mutual relations of the ultimate particles of matter.

Complete lists of Dalton's numerous contributions to scientific collections are included in Dr. Angus Smith's and Dr. Lonsdale's ‘Memoirs’ of him. Before the Manchester Society alone he read no less than 116 papers, many of them of epochal importance. In that entitled ‘Remarks tending to facilitate the Analysis of Spring and Mineral Waters,’ communicated 18 March 1814 (Manch. Memoirs, iii. 59), he explained the principles of volumetric analysis, a method of great value to practical chemists. He published in 1801 (2nd ed. 1803) ‘Elements of English Grammar,’ and wrote the article ‘Meteorology’ in Rees's ‘Cyclopædia.’ A German translation of his ‘New System of Chemical Philosophy’ appeared 1812–13, and a second edition of the first part of vol. i. at London in 1842. The second part of the second volume, by which the work was designed to have been completed, was never written.

[Dr. Angus Smith's Memoir of Dr. Dalton, and Hist. of the Atomic Theory, forming vol. xiii. ser. ii. of Memoirs of Lit. and Phil. Soc. of Manchester, London, 1856; Dr. William C. Henry's Memoirs of the Life and Scientific Researches of John Dalton, printed for the Cavendish Society, London, 1854; Lonsdale's Worthies of Cumberland: John Dalton, London, 1874; Wheeler's Hist. of Manchester, p. 498; Thomson on Daltonian Theory, Annals of Philosophy, ii. 1813, Hist. of Chemistry, ii. 285; Whewell's Hist. of Inductive Sciences, vols. ii. and iii.; Daubeny's Introduction to the Atomic Theory, 2nd ed. Oxford, 1850; Sir H. Roscoe on Dalton's first Table of Atomic Weights, Nature, xi. 52; North Brit. Review, xxvii. 465 (Brewster); Brit. Quart. Review, i. 157 (Dr. G. Wilson); Quart. Review, xcvi. 43; Roy. Soc.'s Cat. Scientific Papers.]  D'ALTON, JOHN (1792–1867), Irish historian, genealogist, and biographer, was born at his father's ancestral mansion, Bessville, co. Westmeath, on 20 June 1792. His mother, Elizabeth Leyne, was also descended from an ancient Irish family. D'Alton was sent to the school of the Rev. Joseph Hutton, Summer Hill, Dublin, and passed the entrance examination of Trinity College, Dublin, in his fourteenth year, 1806. He became a student in 1808, joined the College Historical Society, and gained the prize for poetry. Having graduated at Dublin, he was in 1811 admitted a law student of the Middle Temple, London, and the King's Inns. He was called to the Irish bar in 1813.

He confined himself chiefly to chamber practice. He published a very able treatise on the ‘Law of Tithes,’ and attended the Connaught circuit, having married a lady of that province, Miss Phillips. His reputation for genealogical lore procured him lucrative employment, and he received many fees in the important Irish causes of Malone v. O'Connor, Leamy v. Smith, Jago v. Hungerford, &c. With the exception of an appointment as commissioner of the Loan Fund Board, he held no official position, but a pension of 50l. a year on the civil list, granted while Lord John Russell was prime minister, was some recognition of his literary claims. His first publication was a metrical poem called ‘Dermid, or the Days of Brian Boru.’ It was brought out in a substantial quarto in twelve cantos. In 1827 the Royal Irish Academy offered a prize of 80l. and the Cunningham gold medal for the best essay on the social and political state of the Irish people from the commencement of the christian era to the twelfth century, and their scientific, literary, and artistic development; the researches were to be confined to writings previous to the sixteenth century, and exclusive of those in Irish or other Celtic languages. Full extracts were to be given and all original authorities consulted. D'Alton obtained the highest prize, with the medal, and 40l. was awarded to Dr. Carroll.

D'Alton's essay, which was read 24 Nov. 1828, occupied the first part of vol. xvi. of the ‘Transactions of the Royal Irish Academy.’ In 1831 he also gained the prize offered by the Royal Irish Academy for an account of the reign of Henry II in Ireland. He then employed himself in collecting information regarding druidical stones, the raths and fortresses of the early colonists, especially of the Anglo-Normans, the castles of the Plantagenets, the Elizabethan mansions, the Cromwellian keeps, and the ruins of abbeys. These form the illustrations of