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SUBJECT AREA: Chemical technology, Weapons and armour

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His family came from Germany and he was the son of a music master. He first became interested in science at the age of 14, when visiting his mineralogist uncle in Hamburg, and studied chemistry at the Royal Polytechnic Institution in London. In 1845 he became one of the twenty-six founding students, under A.W.von Hofmann, of the Royal College of Chemistry. Such was his aptitude for the subject that within two years he became von Hermann's assistant and demonstrator. In 1851 Abel was appointed Lecturer in Chemistry, succeeding Michael Faraday, at the Royal Military Academy, Woolwich, and it was while there that he wrote his Handbook of Chemistry, which was co-authored by his assistant, Charles Bloxam.

Abel's four years at the Royal Military Academy served to foster his interest in explosives, but it was during his thirty-four years, beginning in 1854, as Ordnance Chemist at the Royal Arsenal and at Woolwich that he consolidated and developed his reputation as one of the international leaders in his field. In 1860 he was elected a Fellow of the Royal Society, but it was his studies during the 1870s into the chemical changes that occur during explosions, and which were the subject of numerous papers, that formed the backbone of his work. It was he who established the means of storing gun-cotton without the danger of spontaneous explosion, but he also developed devices (the Abel Open Test and Close Test) for measuring the flashpoint of petroleum. He also became interested in metal alloys, carrying out much useful work on their composition. A further avenue of research occurred in 1881 when he was appointed a member of the Royal Commission set up to investigate safety in mines after the explosion that year in the Sealham Colliery. His resultant study on dangerous dusts did much to further understanding on the use of explosives underground and to improve the safety record of the coal-mining industry. The achievement for which he is most remembered, however, came in 1889, when, in conjunction with Sir James Dewar, he invented cordite. This stable explosive, made of wood fibre, nitric acid and glycerine, had the vital advantage of being a "smokeless powder", which meant that, unlike the traditional ammunition propellant, gunpowder ("black powder"), the firer's position was not given away when the weapon was discharged. Although much of the preliminary work had been done by the Frenchman Paul Vieille, it was Abel who perfected it, with the result that cordite quickly became the British Army's standard explosive.

Abel married, and was widowed, twice. He had no children, but died heaped in both scientific honours and those from a grateful country.

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SUBJECT AREA: Medical technology

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After graduating MB and BS from Adelaide University in 1921, he went to Oxford University, England, as a Rhodes Scholar in 1922. Following a period at Cambridge and as a Rockefeller Fellow in the USA, he returned to Cambridge as Lecturer in Pathology. He was appointed to the Chair of Pathology at Sheffield at the age of 33, and to the Sir William Dunne Chair of Pathology at Oxford in 1935.

Although historically his name is inseparable from that of penicillin, his experimental interests and achievements covered practically the whole range of general pathology. He was a determined advocate of the benefits to research of maintaining close contact between different disciplines. He was an early believer in the need to study functional changes in cells as much as the morphological changes that these brought about.

With E. Chain, Florey perceived the potential of Fleming's 1929 note on the bacteria-inhibiting qualities of Penicillium mould. His forthright and dynamic character played a vital part in developing what was perceived to be not just a scientific and medical discovery of unparalleled importance, but a matter of the greatest significance in a war of survival. Between them, Florey and Chain were able to establish the technique of antibiotic isolation and made their findings available to those implementing large-scale fermentation production processes in the USA.

Despite being domiciled in England, he played an active role in Australian medical and educational affairs and was installed as Chancellor of the Australian National University in 1966.

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SUBJECT AREA: Ports and shipping

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After the death of his father, Seppings at the age of 14 moved to his uncle's home in Plymouth, where shortly after (1782) he was apprenticed to the Master Shipwright. His indentures were honoured fully by 1789 and he commenced his climb up the professional ladder of the ship construction department of the Royal Dockyards. In 1797 he became Assistant Master Shipwright at Plymouth, and in 1804 he was appointed Master Shipwright at Chatham. In 1813 Sir William Rule, Surveyor to the Navy, retired and the number of surveyors was increased to three, with Seppings being appointed the junior. Later he was to become Surveyor to the Royal Navy, a post he held until his retirement in 1832. Seppings introduced many changes to ship construction in the early part of the nineteenth century. It is likely that the introduction of these innovations required positive and confident management, and their acceptance tells us much about Seppings. The best-known changes were the round bow and stern in men-of-war and the alteration to framing systems.

The Seppings form of diagonal bracing ensured that wooden ships, which are notorious for hogging (i.e. drooping at the bow and stern), were stronger and therefore able to be built with greater length. This change was complemented by modifications to the floors, frames and futtocks (analogous to the ribs of a ship). These developments were to be taken further once iron composite construction (wooden sheathing on iron frames) was adopted in the United Kingdom mid-century.

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SUBJECT AREA: Weapons and armour

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Educated at Westminster College, in 1904 Tizard went to Magdalen College, Oxford, gaining Firsts in mathematics and chemistry. After a period of time in Berlin with Nernst, he joined the Royal Institution in 1909 to study the colour changes of indicators. From 1911 until 1914 he was a tutorial Fellow of Oriel College, Oxford, but with the outbreak of the First World War he joined first the Royal Garrison Artillery, then, in 1915, the newly formed Royal Flying Corps, to work on the development of bomb-sights. Successively in charge of testing aircraft, a lieutenant-colonel in the Ministry of Munitions and Assistant Controller of Research and Experiments for the Royal Air Force, he returned to Oxford in 1919 and the following year became Reader in Chemical Thermodynamics; at this stage he developed the use of toluene as an air-craft-fuel additive.

In 1922 he was appointed an assistant secretary at the government Department of Industrial and Scientific Research, becoming Principal Assistant Secretary in 1922 and its Permanent Director in 1927; during this time he was also a member of the Aeronautical Research Committee, being Chairman of the latter in 1933–43. From 1929 to 1942 he was Rector of Imperial College. In 1932 he was also appointed Chairman of a committee set up to investigate possible national air-defence systems, and it was largely due to his efforts that the radar proposals of Watson-Watt were taken up and an effective system made operational before the outbreak of the Second World War. He was also involved in various other government activities aimed at applying technology to the war effort, including the dam-buster and atomic bombs.

President of Magdalen College in 1942–7, he then returned again to Whitehall, serving as Chairman of the Advisory Council on Scientific Policy and of the Defence Research Policy Committee. Finally, in 1952, he became Pro-Chan-cellor of Southampton University.

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SUBJECT AREA: Metallurgy

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Soon after graduating from the Ecole des Mines at St-Etienne in 1910, Chevenard joined the Société de Commentry Fourchambault et Decazeville at their steelworks at Imphy, where he remained for the whole of his career. Imphy had for some years specialized in the production of nickel steels. From this venture emerged the first austenitic nickel-chromium steel, containing 6 per cent chromium and 22–4 per cent nickel and produced commercially in 1895. Most of the alloys required by Guillaume in his search for the low-expansion alloy Invar were made at Imphy. At the Imphy Research Laboratory, established in 1911, Chevenard conducted research into the development of specialized nickel-based alloys. His first success followed from an observation that some of the ferro-nickels were free from the low-temperature brittleness exhibited by conventional steels. To satisfy the technical requirements of Georges Claude, the French cryogenic pioneer, Chevenard was then able in 1912 to develop an alloy containing 55–60 per cent nickel, 1–3 per cent manganese and 0.2–0.4 per cent carbon. This was ductile down to −190°C, at which temperature carbon steel was very brittle.

By 1916 Elinvar, a nickel-iron-chromium alloy with an elastic modulus that did not vary appreciably with changes in ambient temperature, had been identified. This found extensive use in horology and instrument manufacture, and even for the production of high-quality tuning forks. Another very popular alloy was Platinite, which had the same coefficient of thermal expansion as platinum and soda glass. It was used in considerable quantities by incandescent-lamp manufacturers for lead-in wires. Other materials developed by Chevenard at this stage to satisfy the requirements of the electrical industry included resistance alloys, base-metal thermocouple combinations, magnetically soft high-permeability alloys, and nickel-aluminium permanent magnet steels of very high coercivity which greatly improved the power and reliability of car magnetos. Thermostatic bimetals of all varieties soon became an important branch of manufacture at Imphy.

During the remainder of his career at Imphy, Chevenard brilliantly elaborated the work on nickel-chromium-tungsten alloys to make stronger pressure vessels for the Haber and other chemical processes. Another famous alloy that he developed, ATV, contained 35 per cent nickel and 11 per cent chromium and was free from the problem of stress-induced cracking in steam that had hitherto inhibited the development of high-power steam turbines. Between 1912 and 1917, Chevenard recognized the harmful effects of traces of carbon on this type of alloy, and in the immediate postwar years he found efficient methods of scavenging the residual carbon by controlled additions of reactive metals. This led to the development of a range of stabilized austenitic stainless steels which were free from the problems of intercrystalline corrosion and weld decay that then caused so much difficulty to the manufacturers of chemical plant.

Chevenard soon concluded that only the nickel-chromium system could provide a satisfactory basis for the subsequent development of high-temperature alloys. The first published reference to the strengthening of such materials by additions of aluminium and/or titanium occurs in his UK patent of 1929. This strengthening approach was adopted in the later wartime development in Britain of the Nimonic series of alloys, all of which depended for their high-temperature strength upon the precipitated compound Ni3Al.

In 1936 he was studying the effect of what is now known as "thermal fatigue", which contributes to the eventual failure of both gas and steam turbines. He then published details of equipment for assessing the susceptibility of nickel-chromium alloys to this type of breakdown by a process of repeated quenching. Around this time he began to make systematic use of the thermo-gravimetrie balance for high-temperature oxidation studies.

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SUBJECT AREA: Civil engineering

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The son of an immigrant merchant, he was educated at the local school, leaving at the age of 13 to take on various jobs, eventually becoming a purser on a Mississippi steamboat. He was struck by the number of wrecks lying in the river; he devised a diving bell and, at the age of 22, set up in business as a salvage engineer. So successful was he at this venture that he was able to retire in three years' time and set up the first glassworks west of the Ohio River. This, however, was a failure and in 1848 he returned to the business of salvage on the Ohio River. He was so successful that he was able to retire permanently in 1857. From the start of the American Civil War in 1861 he recommended to President Lincoln that he should obtain a fleet of armour-plated, steam-powered gunboats to operate on the western rivers. He built seven of these himself, later building or converting a further eighteen. After the end of the war he obtained the contract to design and build a bridge over the Mississippi at St Louis. In this he made use of his considerable knowledge of the river-bed currents. He built a bridge with a 500 ft (150 m) centre span and a clearance of 50 ft (15 m) that was completed in 1874. The three spans are, respectively, 502 ft, 520 ft and 502 ft (153 m, 158 m and 153 m), each being spanned by an arch. The Mississippi river is subject to great changes, both seasonal and irregular, with a range of over 41 ft (12.5 m) between low and high water and a velocity varying from 4 ft (1.2 m) to 12 1/2 ft (3.8 m) per second. The Eads Bridge was completed in 1874 and in the following year Eads was commissioned to open one of the mouths of the Mississippi, for which he constructed a number of jetty traps. He was involved later in attempts to construct a ship railway across the isthmus of Panama. He had been suffering from indifferent health for some years, and this effort was too much for him. He died on 8 March 1887. He was the first American to be awarded the Royal Society of Arts' Albert Medal.

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SUBJECT AREA: Horology

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Born Edmund Beckett Denison, he was educated at Eton and Trinity College, Cambridge, where he studied mathematics, graduating in 1838. He was called to the Bar in 1841 and became a Queen's Counsel in 1854. He built up a large and lucrative practice which gave him the independence to pursue his many interests outside law. His interest in horology may have been stimulated by a friend and fellow lawyer, J.M. Bloxham, who interestingly had invented a gravity escapement with an affinity to the escapement eventually used by Denison. Denison studied horology with his usual thoroughness and by 1850 he had published his Rudimentary Treatise on Clock and Watchmaking. It was natural, therefore, that he should have been invited to be a referee when a disagreement arose over the design of the clock for the new Houses of Parliament. Typically, he interpreted his brief very liberally and designed the clock himself. The most distinctive feature of the clock, in its final form, was the incorporation of a gravity escapement. A gravity escapement was particularly desirable in a public clock as it enabled the pendulum to receive a constant impulse (and thus swing with a constant amplitude), despite the variable forces that might be exerted by the wind on the exposed hands. The excellent performance of the prestigious clock at Westminster made Denison's form of gravity escapement de rigueur for large mechanical public clocks produced in Britain and in many other countries. In 1874 he inherited his father's baronetcy, dropping the Denison name, but later adopted the name Grimthorpe when he was created a Baron in 1886.

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SUBJECT AREA: Mining and extraction technology

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After attending schools in Langres and Dijon, Jobard worked in Groningen and Maastricht as a cadastral officer from 1811 onwards. After the Netherlands had been constituted as a new state in 1814, he became a Dutch citizen in 1815 and settled in Brussels. In 1825, when he had learned of the invention of lithography by Alois Senefelder, he retired and established a renowned lithographic workshop in Belgium, with considerable commercial profit. After the political changes which led to the separation of Belgium from the Netherlands in 1830, he devoted his activities to the progress of science and industry in this country, in the traditional idea of enlightenment. His main aim was to promote all branches of the young economy, to which he contributed with ceaseless energy. He cultivated especially the transfer of technology in many articles he wrote on his various journeys, such as to Britain, France, Germany and Switzerland, and he continued to do so when he became the Director of the Museum of Industry in Brussels in 1841, editing its Bulletin until his death. Jobard, as a member of societies for the encouragement of arts and industry in many countries, published on almost any subject and produced many inventions. Being a restless character by nature, and having, in addition, a strong attitude towards designing and constructing, he also contributed to mining technology in 1828 when he was the first European to practise successfully the Chinese method of rope drilling near Brussels.

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SUBJECT AREA: Ports and shipping

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Barnett studied naval architecture at the University of Glasgow and served an apprenticeship under the yacht designer George L. Watson. This was unusual as most undergraduates tended, then as now, to spend their initial years in the various departments of a shipyard, with concentration on the work of the drawing office. In 1904 Barnett succeeded Watson as Principal of the firm, and was simultaneously appointed Consulting Naval Architect to the Royal National Lifeboat Institution (RNLI), a post he held until his retirement in 1947. During this period many changes in lifeboat design brought increasing efficiency, better ranges of stability and improvements in operational safety. The RNLI recognized the great service of Barnett and his predecessor by naming two lifeboat types after them: the Watson and the Barnett.

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SUBJECT AREA: Ports and shipping

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At the conclusion of his apprenticeship at the Royal Dockyard, Portsmouth, Biles entered the Royal School of Naval Architecture, South Kensington, London; as it was absorbed by the Royal Naval College, he graduated from Greenwich to the Naval Construction Branch, first at Pembroke and later at the Admiralty. From the outset of his professional career it was apparent that he had the intellectual qualities that would enable him to oversee the greatest changes in ship design of all time. He was one of the earliest proponents of the revolutionary work of the hydrodynamicist William Froude.

In 1880 Biles turned to the merchant sector, taking the post of Naval Architect to J. \& G. Thomson (later John Brown \& Co.). Using Froude's Law of Comparisons he was able to design the record-breaking City of Paris of 1887, the ship that started the fabled succession of fast and safe Clyde bank-built North Atlantic liners. For a short spell, before returning to Scotland, Biles worked in Southampton. In 1891 Biles accepted the Chair of Naval Architecture at the University of Glasgow. Working from the campus at Gilmorehill, he was to make the University (the oldest school of engineering in the English-speaking world) renowned in naval architecture. His workload was legendary, but despite this he was admired as an excellent lecturer with cheerful ways which inspired devotion to the Department and the University. During the thirty years of his incumbency of the Chair, he served on most of the important government and international shipping committees, including those that recommended the design of HMS Dreadnought, the ordering of the Cunarders Lusitania and Mauretania and the lifesaving improvements following the Titanic disaster. An enquiry into the strength of destroyer hulls followed the loss of HMS Cobra and Viper, and he published the report on advanced experimental work carried out on HMS Wolf by his undergraduates.

In 1906 he became Consultant Naval Architect to the India Office, having already set up his own consultancy organization, which exists today as Sir J.H.Biles and Partners. His writing was prolific, with over twenty-five papers to professional institutions, sundry articles and a two-volume textbook.

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SUBJECT AREA: Metallurgy

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Brinell graduated as an engineer from Boräs Technical School, and his interest in metallurgy began to develop in 1875 when he became an engineer at the ironworks of Lesjöfors and came under the influence of Gustaf Ekman. In 1882 he was appointed Chief Engineer at the Fagersta Ironworks, where he became one of Sweden's leading experts in the manufacture and heat treatment of tool steels.

His reputation in this field was established in 1885 when he published a paper on the structural changes which occurred in steels when they were heated and cooled, and he was among the first to recognize and define the critical points of steel and their importance in heat treatment. Some of these preliminary findings were first exhibited at Stockholm in 1897. His exhibit at the World Exhibition at Paris in 1900 was far more detailed and there he displayed for the first time his method of hardness determination using a steel-ball indenter. For these contributions he was awarded the French Grand Prix and also the Polhem Prize of the Swedish Technical Society.

He was later concerned with evaluating and developing the iron-ore deposits of north Sweden and was one of the pioneers of the electric blast-furnace. In 1903 he became Chief Engineer of the Jernkontoret and remained there until 1914. In this capacity and as Editor of the Jernkontorets Annaler he made significant contributions to Swedish metallurgy. His pioneer work on abrasion resistance, undertaken long before the term tribology had been invented, gained him the Rinman Medal, awarded by the Jernkontoret in 1920.

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SUBJECT AREA: Medical technology

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Cannon graduated with an arts degree from Harvard University in 1896. He then became a medical student and carried out an investigation into stomach movements using the technique of radio-opaque meals, initially in a cat. He qualified in medicine from Harvard in 1900 and was soon appointed Assistant Professor of Physiology. In 1906 he succeeded to the Chair of Physiology, which he held for thirty-six years.

Apart from his early work, Cannon's demonstration of the humoral transmission of the nerve impulse was fundamental, as were his investigations, including researches on himself and his colleagues, into the relationship between emotion and the sympathetic-adrenal system.

During the First World War he served with both the British and American armies and was decorated.

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SUBJECT AREA: Agricultural and food technology

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The son of a smallholder farmer and self-taught surveyor, William Cobbett was brought up to farm work from an early age. In 1783 he took employment as an attorney's clerk in London, but not finding this to his liking he travelled to Chatham with the intention of joining the Navy. A mistake in "taking the King's shilling" found him in an infantry regiment. After a year's training he was sent out to Nova Scotia and quickly gained the rank of sergeant major. On leaving the Army he brought corruption charges against three officers in his regiment, but did not press with the prosecution. England was not to his taste, and he returned to North America with his wife.

In America Cobbett taught English to the growing French community displaced by the French Revolution. He found American criticism of Britain ill-balanced and in 1796 began to publish a daily newspaper under the title Porcupine's Gazetteer, in which he wrote editorials in defence of Britain. His writings won him little support from the Americans. However, on returning to London in 1800 he was offered, but turned down, the management of a Government newspaper. Instead he began to produce a daily paper called the Porcupine, which was superseded in 1802 by Cobbett's Political Register, this publication continued on a weekly basis until after his death. In 1803 he also began the Parliamentary Debates, which later merged into Hansard, the official report of parliamentary proceedings.

In 1805 Cobbett took a house and 300-acre (120-hectare) farm in Hampshire, from which he continued to write, but at the same time followed the pursuits he most enjoyed. In 1809 his criticism of the punishment given to mutineers in the militia at Ely resulted in his own imprisonment. On his release in 1812 he decided that the only way to remain an independent publisher was to move back to the USA. He bought a farm at Hampstead, Long Island, New York, and published A Year's Residence in America, which contains, amongst other things, an interesting account of a farmer's year.

Returning to Britain in the easier political climate of the 1820s, Cobbett bought a small seed farm in Kensington, then outside London. From there he made a number of journeys around the country, publishing accounts of them in his famous Rural Rides. His experiments and advice on the sowing and cultivation of crops, particularly turnips and swedes, and on forestry, were an important mechanism for the spread of ideas within the UK. He also claimed that he was the first to introduce the acacia and Indian maize to Britain. Much of his writing expresses a concern for the rural poor and he was firmly convinced that only parliamentary reform would achieve the changes needed. His political work and writing led to his election as Member of Parlaiment for Oldham in the 1835 election, which followed the Reform Act of 1832. However, by this time his energy was failing rapidly and he died peacefully at Normandy Farm, near Guildford, at the age of 73.

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SUBJECT AREA: Ports and shipping

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It is believed that Deane was born in Harwich, the son of a master mariner. When 22 years of age, having been trained by Christopher Pett, he was appointed Assistant Master Shipwright at Woolwich Naval Dockyard, indicating an ability as a shipbuilder and also that he had influence behind him. Despite abruptness and a tendency to annoy his seniors, he was acknowledged by no less a man than Pepys (1633–1703) for his skill as a ship designer and -builder, and he was one of the few who could accurately estimate displacements and drafts of ships under construction. While only 26 years old, he was promoted to Master Shipwright of the Naval Base at Harwich and commenced a notable career. When the yard was closed four years later (on the cessation of the threat from the Dutch), Deane was transferred to the key position of Master Shipwright at Portsmouth and given the opportunity to construct large men-of-war. In 1671 he built his first three-decker and was experimenting with underwater hull sheathing and other matters. In 1672 he became a member of the Navy Board, and from then on promotion was spectacular, with almost full responsibility given him for decisions on ship procurement for the Navy. Owing to political changes he was out of office for some years and endured a short period in prison, but on his release he continued to work as a private shipbuilder. He returned to the King's service for a few years before the "Glorious Revolution" of 1688; thereafter little is known of his life, beyond that he died in 1721.

Deane's monument to posterity is his Doctrine of Naval Architecture, published in 1670. It is one of the few books on ship design of the period and gives a clear insight into the rather pedantic procedures used in those less than scientific times. Deane became Mayor of Harwich and subsequently Member of Parliament. It is believed that he was Peter the Great's tutor on shipbuilding during his visit to the Thames in 1698.

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SUBJECT AREA: Metallurgy

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Gibbons was an ironmaster in the Black Country, South Staffordshire, in charge of six blast furnaces owned by the family business. Until Gibbons's innovation in 1832, small changes in the form of the furnace had at times been made, but no one had seriously questioned the square shape of the hearth. Gibbons noticed that a new furnace often worked poorly by improved as time went on. When it was "blown out", i.e. taken out of commission, he found that the corners of the hearth had been rounded off and the sides gouged out, so that it was roughly circular in shape. Gibbons wisely decided to build a blast furnace with a round hearth alongside an existing one with a traditionally shaped hearth and work them in exactly the same conditions. The old furnace produced 75 tons of iron in a week, about normal for the time, while the new one produced 100 tons. Further improvements followed and in 1838 a fellow ironmaster in the same district, T. Oakes, considerably enlarged the furnace, its height attaining no less than 60ft (18m). As a result, output soared to over 200 tons a week. Most other ironmasters adopted the new form with enthusiasm and it proved to be the basis for the modern blast furnace. Gibbons made another interesting innovation: he began charging his furnace with the "rubbish", slag or cinder, from earlier ironmaking operations. It contained a significant amount of iron and was cheaper to obtain than iron ore, as it was just lying around in heaps. Some ironmasters scorned to use other people's throw-outs, but Gibbons sensibly saw it as a cheap source of iron; it was a useful source for some years during the nineteenth century but its use died out when the heaps were used up. Gibbons published an account of his improvements in ironmaking in a pamphlet entitled Practical Remarks on the Construction of the Staffordshire Blast Furnace.

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SUBJECT AREA: Horology

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Graham's father died soon after his birth, so he was raised by his brother. In 1688 he was apprenticed to the London clockmaker Henry Aske, and in 1695 he gained his freedom. He was employed as a journeyman by Tompion in 1696 and later married his niece. In 1711 he formed a partnership with Tompion and effectively ran the business in Tompion's declining years; he took over the business after Tompion died in 1713. In addition to his horological interests he also made scientific instruments, specializing in those for astronomical use. As a person, he was well respected and appears to have lived up to the epithet "Honest George Graham". He befriended John Harrison when he first went to London and lent him money to further his researches at a time when they might have conflicted with his own interests.

The two common forms of escapement in use in Graham's time, the anchor escapement for clocks and the verge escapement for watches, shared the same weakness: they interfered severely with the free oscillation of the pendulum and the balance, and thus adversely affected the timekeeping. Tompion's two frictional rest escapements, the dead-beat for clocks and the horizontal for watches, had provided a partial solution by eliminating recoil (the momentary reversal of the motion of the timepiece), but they had not been successful in practice. Around 1720 Graham produced his own much improved version of the dead-beat escapement which became a standard feature of regulator clocks, at least in Britain, until its supremacy was challenged at the end of the nineteenth century by the superior accuracy of the Riefler clock. Another feature of the regulator clock owed to Graham was the mercury compensation pendulum, which he invented in 1722 and published four years later. The bob of this pendulum contained mercury, the surface of which rose or fell with changes in temperature, compensating for the concomitant variation in the length of the pendulum rod. Graham devised his mercury pendulum after he had failed to achieve compensation by means of the difference in expansion between various metals. He then turned his attention to improving Tompion's horizontal escapement, and by 1725 the cylinder escapement existed in what was virtually its final form. From the following year he fitted this escapement to all his watches, and it was also used extensively by London makers for their precision watches. It proved to be somewhat lacking in durability, but this problem was overcome later in the century by using a ruby cylinder, notably by Abraham Louis Breguet. It was revived, in a cheaper form, by the Swiss and the French in the nineteenth century and was produced in vast quantities.

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See also: Barlow, Edward; Guillaume, Charles-Edouard

SUBJECT AREA: Architecture and building

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A year after he began practice as an architect, Gropius was responsible for the pace-setting Fagus shoe-last factory at Alfeld-an-der-Leine in Germany, one of the few of his buildings to survive the Second World War. Today the building does not appear unusual, but in 1911 it was a revolutionary prototype, heralding the glass curtain walled method of non-load-bearing cladding that later became ubiquitous. Made from glass, steel and reinforced concrete, this factory initiated a new concept, that of the International school of modern architecture.

In 1919 Gropius was appointed to head the new School of Art and Design at Weimar, the Staatliches Bauhaus. The school had been formed by an amalgamation of the Grand Ducal schools of fine and applied arts founded in 1906. Here Gropius put into practice his strongly held views and he was so successful that this small college, which trained only a few hundred students in the limited years of its existence, became world famous, attracting artists, architects and students of quality from all over Europe.

Gropius's idea was to set up an institution where students of all the arts and crafts could work together and learn from one another. He abhorred the artificial barriers that had come to exist between artists and craftsmen and saw them all as interdependent. He felt that manual dexterity was as essential as creative design. Every Bauhaus student, whatever the individual's field of work or talent, took the same original workshop training. When qualified they were able to understand and supervise all the aesthetic and constructional processes that made up the scope of their work.

In 1924, because of political changes, the Weimar Bauhaus was closed, but Gropius was invited to go to Dessau to re-establish it in a new purpose-built school which he designed. This group of buildings became a prototype that designers of the new architectural form emulated. Gropius left the Bauhaus in 1928, only a few years before it was finally closed due to the growth of National Socialism. He moved to England in 1934, but because of a lack of architectural opportunities and encouragement he continued on his way to the USA, where he headed the Department of Architecture at Harvard University's Graduate School of Design from 1937 to 1952. After his retirement from there Gropius formed the Architect's Collaborative and, working with other architects such as Marcel Breuer and Pietro Belluschi, designed a number of buildings (for example, the US Embassy in Athens (1960) and the Pan Am Building in New York (1963)).

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SUBJECT AREA: Horology, Ports and shipping

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John Harrison was the son of a carpenter and was brought up to that trade. He was largely self-taught and learned mechanics from a copy of Nicholas Saunderson's lectures that had been lent to him. With the assistance of his younger brother, James, he built a series of unconventional clocks, mainly of wood. He was always concerned to reduce friction, without using oil, and this influenced the design of his "grasshopper" escapement. He also invented the "gridiron" compensation pendulum, which depended on the differential expansion of brass and steel. The excellent performance of his regulator clocks, which incorporated these devices, convinced him that they could also be used in a sea dock to compete for the longitude prize. In 1714 the Government had offered a prize of £20,000 for a method of determining longitude at sea to within half a degree after a voyage to the West Indies. In theory the longitude could be found by carrying an accurate timepiece that would indicate the time at a known longitude, but the requirements of the Act were very exacting. The timepiece would have to have a cumulative error of no more than two minutes after a voyage lasting six weeks.

In 1730 Harrison went to London with his proposal for a sea clock, supported by examples of his grasshopper escapement and his gridiron pendulum. His proposal received sufficient encouragement and financial support, from George Graham and others, to enable him to return to Barrow and construct his first sea clock, which he completed five years later. This was a large and complicated machine that was made out of brass but retained the wooden wheelwork and the grasshopper escapement of the regulator clocks. The two balances were interlinked to counteract the rolling of the vessel and were controlled by helical springs operating in tension. It was the first timepiece with a balance to have temperature compensation. The effect of temperature change on the timekeeping of a balance is more pronounced than it is for a pendulum, as two effects are involved: the change in the size of the balance; and the change in the elasticity of the balance spring. Harrison compensated for both effects by using a gridiron arrangement to alter the tension in the springs. This timekeeper performed creditably when it was tested on a voyage to Lisbon, and the Board of Longitude agreed to finance improved models. Harrison's second timekeeper dispensed with the use of wood and had the added refinement of a remontoire, but even before it was tested he had embarked on a third machine. The balance of this machine was controlled by a spiral spring whose effective length was altered by a bimetallic strip to compensate for changes in temperature. In 1753 Harrison commissioned a London watchmaker, John Jefferys, to make a watch for his own personal use, with a similar form of temperature compensation and a modified verge escapement that was intended to compensate for the lack of isochronism of the balance spring. The time-keeping of this watch was surprisingly good and Harrison proceeded to build a larger and more sophisticated version, with a remontoire. This timekeeper was completed in 1759 and its performance was so remarkable that Harrison decided to enter it for the longitude prize in place of his third machine. It was tested on two voyages to the West Indies and on both occasions it met the requirements of the Act, but the Board of Longitude withheld half the prize money until they had proof that the timekeeper could be duplicated. Copies were made by Harrison and by Larcum Kendall, but the Board still continued to prevaricate and Harrison received the full amount of the prize in 1773 only after George III had intervened on his behalf.

Although Harrison had shown that it was possible to construct a timepiece of sufficient accuracy to determine longitude at sea, his solution was too complex and costly to be produced in quantity. It had, for example, taken Larcum Kendall two years to produce his copy of Harrison's fourth timekeeper, but Harrison had overcome the psychological barrier and opened the door for others to produce chronometers in quantity at an affordable price. This was achieved before the end of the century by Arnold and Earnshaw, but they used an entirely different design that owed more to Le Roy than it did to Harrison and which only retained Harrison's maintaining power.

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See also: Burgi, Jost; Huygens, Christiaan

SUBJECT AREA: Broadcasting, Telecommunications

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Brought up in poor, almost Dickensian, circumstances, at the age of 13 years Heaviside, a nephew by marriage of Sir Charles Wheatstone, went to Camden House Grammar School. There he won a medal for science, but he was forced to leave because his parents could not afford the fees. After a year of private study, he began his working life in Newcastle in 1870 as a telegraph operator for an Anglo-Dutch cable company, but he had to give up after only four years because of increasing deafness. He therefore proceeded to spend his time studying theoretical aspects of electrical transmission and communication, and moved to Devon with his parents in 1889. Because the operation of many electrical circuits involves transient phenomena, he found it necessary to develop what he called operational calculus (which was essentially a form of the Laplace transform calculus) in order to determine the response to sudden voltage and current changes. In 1893 he suggested that the distortion that occurred on long-distance telephone lines could be reduced by adding loading coils at regular intervals, thus creating a matched-transmission line. Between 1893 and 1912 he produced a series of writings on electromagnetic theory, in one of which, anticipating a conclusion of Einstein's special theory of relativity, he put forward the idea that the mass of an electric charge increases with its velocity. When it was found that despite the curvature of the earth it was possible to communicate over very great distances using radio signals in the so-called "short" wavebands, Heaviside suggested the presence of a conducting layer in the ionosphere that reflected the waves back to earth. Since a similar suggestion had been made almost at the same time by Arthur Kennelly of Harvard, this layer became known as the Kennelly-Heaviside layer.

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See also: Appleton, Sir Edward Victor