section of rupture or fracture, and made it subservient to the computation of the strength of a beam of given dimensions. His conception of the true mechanical principle by which the position of the line could be determined has long obtained general acceptance. In 1828 he read before the same society an important paper ‘On the Forms of the Catenary in Suspension Bridges,’ and in 1830 one on ‘Theoretical and Practical Researches to ascertain the Strength and best forms of Iron Beams,’ one of the most valuable contributions to the history of the strength of materials ever made. From the theoretical expositions there given of the neutral line, the experiments to determine the strongest beam were devised and successfully carried out, resulting in the discovery of what is known as ‘Hodgkinson's beam,’ which has been described as the pole star for engineers and builders. Among his other contributions to the British Association are two on the temperature of the earth in the deep mines of Lancashire and Cheshire (Reports, 1839–40). In the ‘Philosophical Transactions’ for 1840 he wrote ‘On the Strength of Pillars of Cast Iron and other Materials,’ which secured him the royal medal of the Royal Society and his election as F.R.S. He rendered important service to Robert Stephenson in the construction of the Conway and Britannia tubular bridges by fixing the best forms and dimensions of tubes. He edited the fourth edition of Tredgold's work on the strength of cast iron, 1842, and published a volume of his own, ‘Experimental Researches on the Strength and other Properties of Cast Iron,’ in 1846. Many of the experiments were, as he states in his preface, carried out at the works of Mr. W. Fairbairn. He worked from 1847 to 1849 as one of the royal commissioners to inquire into the application of iron to railway structures. His own contributions to the commissioners' report occupy a prominent position, and elicited the special thanks of his fellow-commissioners. In 1847 he was appointed professor of the mechanical principles of engineering at University College, London, where, however, his lectures were deprived of a large share of efficiency by his nervous hesitancy of speech. He was a member of the Geological Society and of the Royal Irish Academy, and honorary member of the Institute of Civil Engineers (elected 1851) and of other societies. From 1848 to 1850 he was president of the Manchester Literary and Philosophical Society.
He was twice married, but had no children. His first wife was Catherine, daughter of the Rev. William Johns of Manchester; his second the daughter of Henry Holditch, captain in the Cheshire militia. In his last years, when he had become enfeebled both physically and mentally, he occupied himself in arranging his papers with a view to their publication in a collected form, but he did not live to complete the task. He died at Higher Broughton, Manchester, on 18 June 1861, and was buried at his native village.
[Life, by R. Rawson, in Memoirs of Manchester Lit. and Phil. Soc. 3rd ser. ii. 145; also in Smithsonian Report for 1868; Proc. of Institute of Civil Engineers, xxi. 542; Todhunter's Hist. of the Elasticity and Strength of Materials, 1886, vol. i.; Pole's Life of Sir W. Fairbairn, 1877; R. Angus Smith's Centenary of Science in Manchester, 1883. The Royal Society's Catalogue of Scientific Papers gives a list of nineteen papers by Hodgkinson. A summary of his experiments will be found in Barlow's Strength of Materials.]
HODGKINSON, GEORGE CHRISTOPHER (1816–1880), meteorologist and writer on education, studied at Trinity College, Cambridge, graduating B.A. (fourteenth wrangler) in 1837, and M.A. in 1842. He became principal of the Royal Agricultural College at Cirencester, then principal of the Diocesan Training College at York, and from 1864 to 1876 was head-master of the King Edward grammar school at Louth. He was also secretary of the National Society. Hodgkinson was presented to the rectory of Screveton, Nottinghamshire, in 1876. Hodgkinson married a granddaughter of Sir James Ross. He died at Car Colston, Nottinghamshire, on 25 April 1880.
Hodgkinson was an Alpine climber. In 1862 he contributed ‘Hypsometry and the Aneroid’ to ‘Peaks, Passes, and Glaciers,’ published for the Alpine Club (1862), vol. ii. (2nd ser.). Hodgkinson showed a practical as well as theoretical knowledge of the mechanism and application of aneroids, and recommended their use in mountain exploration, not only in the interests of meteorology, but for the convenience of the tourist. He made a series of astronomical observations on the summit of Mont Blanc, towards which he received from the Royal Society several grants ‘for the construction of his own scientific instruments and the modification of others.’ He had some correspondence with the astronomer royal as to the most effective mode of registering the amount and intensity of sunshine. Besides sermons and tracts Hodgkinson also published, in reply to the Archbishop of York and Bishop of Ripon, a defence of the teaching of the Diocesan College at York (1854), and some pamphlets on the examinations for the Indian civil service, approving open competition.
