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81 Rosenhain, Walter
SUBJECT AREA: Metallurgy[br]b. 24 August 1875 Berlin, Germanyd. 17 March 1934 Kingston Hill, Surrey, England[br]German metallurgist, first Superintendent of the Department of Metallurgy and Metallurgical Chemistry at the National Physical Laboratory, Teddington, Middlesex.[br]His family emigrated to Australia when he was 5 years old. He was educated at Wesley College, Melbourne, and attended Queen's College, University of Melbourne, graduating in physics and engineering in 1897. As an 1851 Exhibitioner he then spent three years at St John's College, Cambridge, under Sir Alfred Ewing, where he studied the microstructure of deformed metal crystals and abandoned his original intention of becoming a civil engineer. Rosenhain was the first to observe the slip-bands in metal crystals, and in the Bakerian Lecture delivered jointly by Ewing and Rosenhain to the Royal Society in 1899 it was shown that metals deformed plastically by a mechanism involving shear slip along individual crystal planes. From this conception modern ideas on the plasticity and recrystallization of metals rapidly developed. On leaving Cambridge, Rosenhain joined the Birmingham firm of Chance Brothers, where he worked for six years on optical glass and lighthouse-lens systems. A book, Glass Manufacture, written in 1908, derives from this period, during which he continued his metallurgical researches in the evenings in his home laboratory and published several papers on his work.In 1906 Rosenhain was appointed Head of the Metallurgical Department of the National Physical Laboratory (NPL), and in 1908 he became the first Superintendent of the new Department of Metallurgy and Metallurgical Chemistry. Many of the techniques he introduced at Teddington were described in his Introduction to Physical Metallurgy, published in 1914. At the outbreak of the First World War, Rosenhain was asked to undertake work in his department on the manufacture of optical glass. This soon made it possible to manufacture optical glass of high quality on an industrial scale in Britain. Much valuable work on refractory materials stemmed from this venture. Rosenhain's early years at the NPL were, however, inseparably linked with his work on light alloys, which between 1912 and the end of the war involved virtually all of the metallurgical staff of the laboratory. The most important end product was the well-known "Y" Alloy (4% copper, 2% nickel and 1.5% magnesium) extensively used for the pistons and cylinder heads of aircraft engines. It was the prototype of the RR series of alloys jointly developed by Rolls Royce and High Duty Alloys. An improved zinc-based die-casting alloy devised by Rosenhain was also used during the war on a large scale for the production of shell fuses.After the First World War, much attention was devoted to beryllium, which because of its strength, lightness, and stiffness would, it was hoped, become the airframe material of the future. It remained, however, too brittle for practical use. Other investigations dealt with impurities in copper, gases in aluminium alloys, dental alloys, and the constitution of alloys. During this period, Rosenhain's laboratory became internationally known as a centre of excellence for the determination of accurate equilibrium diagrams.[br]Principal Honours and DistinctionsFRS 1913. President, Institute of Metals 1828–30. Iron and Steel Institute Bessemer Medal, Carnegie Medal.Bibliography1908, Glass Manufacture.1914, An Introduction to the Study of Physical Metallurgy, London: Constable. Rosenhain published over 100 research papers.Further ReadingJ.L.Haughton, 1934, "The work of Walter Rosenhain", Journal of the Institute of Metals 55(2):17–32.ASD -
82 Theophilus Presbyter
[br]fl. late eleventh/early twelfth century[br]German author of the most detailed medieval treatise relating to technology.[br]The little that is known of Theophilus is what can be inferred from his great work, De diversis artibus. He was a Benedictine monk and priest living in north-west Germany, probably near an important art centre. He was an educated man, conversant with scholastic philosophy and at the same time a skilled, practising craftsman. Even his identity is obscure: Theophilus is a pseudonym, possibly for Roger of Helmarshausen, for the little that is known of both is in agreement.Evidence in De diversis suggests that it was probably composed during 1110 to 1140. White (see Further Reading) goes on to suggest late 1122 or early 1123, on the grounds that Theophilus only learned of St Bernard of Clairvaulx's diatribe against lavish church ornamentation during the writing of the work, for it is only in the preface to Book 3 that Theophilus seeks to justify his craft. St Bernard's Apologia can be dated late 1122. No other medieval work on art combines the comprehensive range, orderly presentation and attention to detail as does De diversis. It has been described as an encyclopedia of medieval skills and crafts. It also offers the best and often the only description of medieval technology, including the first direct reference to papermaking in the West, the earliest medieval account of bell-founding and the most complete account of organ building. Many metallurgical techniques are described in detail, such as the making of a crucible furnace and bloomery hearth.The treatise is divided into three books, the first on the materials and art of painting, the second on glassmaking, including stained glass, glass vessels and the blown-cylinder method for flat glass, and the final and longest book on metalwork, including working in iron, copper, gold and silver for church use, such as chalices and censers. The main texts are no mere compilations, but reveal the firsthand knowledge that can only be gained by a skilled craftsman. The prefaces to each book present perhaps the only medieval expression of an artist's ideals and how he sees his art in relation to the general scheme of things. For Theophilus, his art is a gift from God and every skill an act of praise and piety. Theophilus is thus an indispensable source for medieval crafts and technology, but there are indications that the work was also well known at the time of its composition and afterwards.[br]BibliographyThe Wolfenbuttel and Vienna manuscripts of De diversis are the earliest, both dating from the first half of the twelfth century, while the British Library copy, in an early thirteenth-century hand, is the most complete. Two incomplete copies from the thirteenth century held at Cambridge and Leipzig offer help in arriving at a definitive edition.There are several references to De diversis in sixteenth-century printed works, such as Cornelius Agrippa (1530) and Josias Simmler (1585). The earliest printed edition ofDe diversis was prepared by G.H.Lessing in 1781 with the title, much used since, Diversarium artium schedula.There are two good recent editions: Theophilus: De diversis artibus. The Various Arts, 1964, trans. with introd. by C.R.Dodwell, London: Thomas Nelson, and On Diverse Arts. The Treatise of Theophilus, 1963, trans. with introd. and notes by J.G.Harthorne and C.S.Smith, Chicago University Press.Further ReadingLynn White, 1962, "Theophilus redivivus", Technology and Culture 5:224–33 (a comparative review of Theophilus (op. cit.) and On Diverse Arts (op. cit.)).LRD
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