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41 Guo Shoujing (Kuo Shou-Ching)
[br]b. 1231 Chinad. 1316 China[br]Chinese mathematician, astronomer and civil engineer.[br]First, from 1262, he was engaged in hydraulic-engineering works for Kublai Khan. He began astronomical and calendrical investigations in 1276, and became the greatest astronomer of the Yuan dynasty. He perfected interpolation formulae (a method of finite differences) and was the founder of the study of spherical trigonometry in China; this was applied to the circles of the heavenly sphere. He planned the Ji Zhou, the summit section of the Grand Canal through the Shandong foothills, in 1283. Although the canal had to await further improvement before it could become fully effective, it was nevertheless the world's first successful entirely artificial summit canal.Guo Shoujing was responsible for the construction of the Tong Hui He (Channel of Communicating Grace) canal with twenty lock gates in 1293, in addition to the overhaul of the entire Grand Canal. He constructed a number of devices, including 40 ft (12 m) gnomons in 1276, with which he made some of the most accurate measurements of the sun's solstitial shadows, the results of which were collected in a book that is now lost. Between 1276 and 1279 he also constructed at least one water-driven mechanical escapement clock with sophisticated jack work, and the Beijing observatory and its equipment.[br]Further ReadingJ.Needham, Science and Civilisation in China, Cambridge: Cambridge University Press, 1959–1971, vols III, pp. 48–50, 109–10, 294, 296, 299, 349, 350; IV. 2, pp. 504–5; IV.3, pp. 312ff., 319, 355; Heavenly Clockwork, 1960, pp. 134, 136ff., 159, 160, 163;Clerks and Craftsmen in China and the West, 1970, pp. 2, 5, 9–10, 16, 96, 398.LRDBiographical history of technology > Guo Shoujing (Kuo Shou-Ching)
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42 Izod, Edwin Gilbert
SUBJECT AREA: Metallurgy[br]b. 17 July 1876 Portsmouth, Englandd. 2 October 1946 England[br]English engineer who devised the notched-bar impact test named after him.[br]After a general education at Vickery's School at Southsea, Izod (who pronounced his name Izzod, not Izod) started his career as a premium apprentice at the works of Maudslay, Sons and Field at Lambeth in January 1893. When in 1995 he was engaged in the installation of machinery in HMS Renown at Pembroke, he gained some notoriety for his temerity in ordering Rear Admiral J.A.Fisher, who had no pass, out of the main engine room. He subsequently worked at Portsmouth Dockyard where the battleships Caesar and Gladiator were being engined by Maudslay's. From 1898 to 1900 Izod worked as a Demonstrator in the laboratories of University College London, and he was then engaged by Captain H. Riall Sankey as his Personal Assistant at the Rugby works of Willans and Robinson. Soon after going to Rugby, Izod was asked by Sankey to examine a failed gun barrel and try to ascertain why it burst in testing. Conventional mechanical testing did not reveal any significant differences in the properties of good and bad material. Izod found, however, that, when specimens from the burst barrel were notched, gripped in a vice, and then struck with a hammer they broke in a brittle manner, whereas sounder material merely bent plastically. From these findings his well-known notched-bar impact test emerged. His address to the British Association in September 1903 described the test and his testing machine, and was subsequently published in Engineering. Izod never claimed any priority for this method of test, and generously acknowledged his predecessors in this field, Swedenborg, Fremont, Arnold and Bent Russell. The Izod Test was rapidly adopted by the English-speaking world, although Izod himself, being a busy man, did little to publicize his work, which was introduced to the engineering world largely through the efforts of Captain Sankey. Izod became Assistant Managing Director at Willans, and in 1910 was appointed Chief Consulting Mechanical and Electrical Engineer to the Central Mining Corporation at Johannesburg. He became Managing Director of the Rand Mines in 1918, and returned to the UK in 1927 to become the Managing Director of Weymann Motor Bodies Ltd of Addlestone. As Chairman of this company he extended its activitiesconsiderably.[br]Principal Honours and DistinctionsMBE. Member of the Iron and Steel Institute.Further Reading1903, "Testing brittleness of steel", Engineering (25 September): 431–2.ASD -
43 Riche, Gaspard-Clair-François-Marie, Baron de Prony
SUBJECT AREA: Electronics and information technology[br]b. c. 1755 France d. c. 1839[br]French mathematician who used the method of differences to calculate logarithms and trigonometric functions,[br]Whilst Directeur of the Bureau du Cadastre, Prony was made responsible for a project to determine the trigonometric functions of the centesimal units of 90°, i.e. the right angle was successively divided into 100 grades containing 100 minutes, which in turn each consisted of 100 seconds. This work produced tables (known as the Table de Cadastre) of the natural sines to twenty-two decimal places and the logarithms of sines and tangents to fourteen places. Although the tables as calculated were never published, tables based on them (presumably derived for the more familiar degree, minute and second sub-divisions of a right-angle by interpolation) have since appeared.KFBiographical history of technology > Riche, Gaspard-Clair-François-Marie, Baron de Prony
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