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21 Pliny the Elder (Gaius Plinius Secundus)
SUBJECT AREA: Metallurgy[br]b. c. 23 AD Como, Italyd. 25 August 79 AD near Pompeii, Italy[br]Roman encyclopedic writer on the natural world.[br]Pliny was well educated in Rome, and for ten years or so followed a military career with which he was able to combine literary work, writing especially on historical subjects. He completed his duties c. 57 AD and concentrated on writing until he resumed his official career in 69 AD with administrative duties. During this last phase he began work on his only extant work, the thirty-seven "books" of his Historia Naturalis (Natural History), each dealing with a broad subject such as astronomy, geography, mineralogy, etc. His last post was the command of the fleet based at Misenum, which came to an end when he sailed too near Vesuvius during the eruption that engulfed Pompeii and he was overcome by the fumes.Pliny developed an insatiable curiosity about the natural world. Unlike the Greeks, the Romans made few original contributions to scientific thought and observation, but some made careful compilations of the learning and observations of Greek scholars. The most notable and influential of these was the Historia Naturalis. To the ideas about the natural world gleaned from earlier Greek authors, he added information about natural history, mineral resources, crafts and some technological processes, such as the extraction of metals from their ores, reported to him from the corners of the Empire. He added a few observations of his own, noted during travels on his official duties. Not all the reports were reliable, and the work often presents a tangled web of fact and fable. Gibbon described it as an immense register in which the author has "deposited the discoveries, the arts, and the errors of mankind". Pliny was indefatigable in his relentless note-taking, even dictating to his secretary while dining.During the Dark Ages and early Middle Ages in Western Europe, Pliny's Historia Naturalis was the largest known collection of facts about the natural world and was drawn upon freely by a succession of later writers. Its influence survived the influx into Western Europe, from the twelfth century, of translations of the works of Greek and Arab scholars. After the invention of printing in the middle of the fifteenth century, Pliny was the first work on a scientific subject to be printed, in 1469. Many editions followed and it may still be consulted with profit for its insights into technical knowledge and practice in the ancient world.[br]BibliographyThe standard Latin text with English translation is that edited by H.Rackham et al.(1942– 63, Loeb Classical Library, London: Heinemann, 10 vols). The French version is by A.Further ReadingThe editions mentioned above include useful biographical and other details. For special aspects of Pliny, see K.C.Bailey, 1929–32, The Elder Pliny's Chapters on Chemical Subjects, London, 2 vols.LRDBiographical history of technology > Pliny the Elder (Gaius Plinius Secundus)
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22 Richard of Wallingford, Abbot
SUBJECT AREA: Horology[br]b. 1291/2 Wallingford, Englandd. 23 May 1336 St Albans, Hertfordshire, England[br]English cleric, mathematician and astronomer who produced the earliest mechanical clock of which there is detailed knowledge.[br]Richard, the son of a blacksmith, was adopted by the Prior of Wallingford when his father died and educated at Oxford. He then joined the monastery at St Albans and was ordained as a priest in 1317. After a further period at Oxford studying mathematics and astronomy he returned to St Albans as Abbot in 1327. Shortly after he had been elected Abbot he started work on a very elaborate astronomical clock. The escapement and the striking mechanism of this clock were unusual. The former was a variation on the verge escapement, and the hour striking (up to twenty-four) was controlled by a series of pins laid out in a helical pattern on a drum. However, timekeeping was of secondary importance as the main purpose of the clock was to show the motion of the Sun, Moon and planets (the details of the planet mechanism are lost) and to demonstrate eclipses. This was achieved in a very precise manner by a series of ingenious mechanisms, such as the elliptical wheel that was used to derive the variable motion of the sun.Richard died of leprosy, which he had contracted during a visit to obtain papal confirmation of his appointment, and the clock was completed after his death. The last recorded reference to it was made by John Leyland, shortly before the dissolution of the monasteries. It is now known only from incomplete manuscript copies of Richard's treatise. A modern reconstruction has been made based upon J.D.North's interpretation of the manuscript.[br]BibliographyFor the drafts of Richard's Treatise on the Clock, with translation and commentary, see J.D.North, 1976, Richard of Wallingford, 3 vols, Oxford.Further ReadingSee J.D.North's definitive work above: for biographical information see Vol. 2, pp. 1–16. Most of the shorter accounts appeared before the publication of North's treatise and are therefore of more limited use.G.White, 1978, "Evolution of the epicyclic gear—part 2", Chartered Mechanical Engineer (April): 85–8 (an account of Richard's use of epicyclic gearing).DVBiographical history of technology > Richard of Wallingford, Abbot
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23 Thomson, Elihu
SUBJECT AREA: Electricity[br]b. 29 March 1853 Manchester, Englandd. 13 March 1937 Swampscott, Massachusetts, USA[br]English (naturalized) American electrical engineer and inventor.[br]Thomson accompanied his parents to Philadelphia in 1858; he received his education at the Central High School there, and afterwards remained as a teacher of chemistry. At this time he constructed several dynamos after studying their design, and was invited by the Franklin Institute to give lectures on the subject. After observing an arc-lighting system operating commercially in Paris in 1878, he collaborated with Edwin J. Houston, a senior colleague at the Central High School, in working out the details of such a system. An automatic regulating device was designed which, by altering the position of the brushes on the dynamo commutator, maintained a constant current irrespective of the number of lamps in use. To overcome the problem of commutation at the high voltages necessary to operate up to forty arc lamps in a series circuit, Thomson contrived a centrifugal blower which suppressed sparking. The resulting system was efficient and reliable with low operating costs. Thomson's invention of the motor meter in 1882 was the first of many such instruments for the measurement of electrical energy. In 1886 he invented electric resistance welding using low-voltage alternating current derived from a transformer of his own design. Thomson's work is recorded in his technical papers and in the 700plus patents granted for his inventions.The American Electric Company, founded to exploit the Thomson patents, later became the Thomson-Houston Company, which was destined to be a leader in the electrical manufacturing industry. They entered the field of electric power in 1887, supplying railway equipment and becoming a major innovator of electric railways. Thomson-Houston and Edison General Electric were consolidated to form General Electric in 1892. Thomson remained associated with this company throughout his career.[br]Principal Honours and DistinctionsChevalier and Officier de la Légion d'honneur 1889. American Academy of Arts and Sciences Rumford Medal 1901. American Institute of Electrical Engineers Edison Medal 1909. Royal Society Hughes Medal 1916. Institution of Electrical Engineers Kelvin Medal 1923, Faraday Medal 1927.Bibliography1934, "Some highlights of electrical history", Electrical Engineering 53:758–67 (autobiography).Further ReadingD.O.Woodbury, 1944, Beloved Scientist, New York (a full biography). H.C.Passer, 1953, The Electrical Manufacturers: 1875–1900, Cambridge, Mass, (describes Thomson's industrial contribution).K.T.Compton, 1940, Biographical Memoirs of Elihu Thomson, Washington, DCovides an abridged list of Thomson's papers and patents).GW -
24 Warren, Henry Ellis
SUBJECT AREA: Horology[br]b. 21 May 1872 Boston, Massachusetts, USAd. 21 September 1957 Ashland, Massachusetts, USA[br]American electrical engineer who invented the mains electric synchronous clock.[br]Warren studied electrical engineering at the Boston Institute of Technology (later to become the Massachusetts Institute of Technology) and graduated in 1894. In 1912 he formed the Warren Electric Clock Company to make a battery-powered clock that he had patented a few years earlier. The name was changed to the Warren Telechron (time at a distance) Company after he had started to produce synchronous clocks.In 1840 Charles Wheatstone had produced an electric master clock that produced an alternating current with a frequency of one cycle per second and which was used to drive slave dials. This system was not successful, but when Ferranti introduced the first alternating current power generator at Deptford in 1895 Hope-Jones saw in it a means of distributing time. This did not materialize immediately because the power generators did not control the frequency of the current with sufficient accuracy, and a reliable motor whose speed was related to this frequency was not available. In 1916 Warren solved both problems: he produced a reliable self-starting synchronous electric motor and he also made a master clock which could be used at the power station to control accurately the frequency of the supply. Initially the power-generating companies were reluctant to support the synchronous clock because it imposed a liability to control the frequency of the supply and the gain was likely to be small because it was very frugal in its use of power. However, with the advent of the grid system, when several generators were connected together, it became imperative to control the frequency; it was realized that although the power consumption of individual clocks was small, collectively it could be significant as they ran continuously. By the end of the 1930s more than half the clocks sold in the USA were of the synchronous type. The Warren synchronous clock was introduced into Great Britain in 1927, following the setting up of a grid system by the Electricity Commission.[br]Principal Honours and DistinctionsFranklin Institute John Price Wetherill Medal. American Institute of Electrical Engineers Lamme Medal.BibliographyThe patents for the synchronous motor are US patent nos. 1,283,432, 1,283,433 and 1,283,435, and those for the master clock are 1,283,431, 1,409,502 and 1,502,493 of 29 October 1918 onwards.1919, "Utilising the time characteristics of alternating current", Transactions of the American Institute of Electrical Engineers 38:767–81 (Warren's first description of his system).Further ReadingJ.M.Anderson, 1991, "Henry Ellis Warren and his master clocks", National Association of Watch and Clock Collectors Bulletin 33:375–95 (provides biographical and technical details).DV
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