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81 Stephenson, Robert
[br]b. 16 October 1803 Willington Quay, Northumberland, Englandd. 12 October 1859 London, England[br]English engineer who built the locomotive Rocket and constructed many important early trunk railways.[br]Robert Stephenson's father was George Stephenson, who ensured that his son was educated to obtain the theoretical knowledge he lacked himself. In 1821 Robert Stephenson assisted his father in his survey of the Stockton \& Darlington Railway and in 1822 he assisted William James in the first survey of the Liverpool \& Manchester Railway. He then went to Edinburgh University for six months, and the following year Robert Stephenson \& Co. was named after him as Managing Partner when it was formed by himself, his father and others. The firm was to build stationary engines, locomotives and railway rolling stock; in its early years it also built paper-making machinery and did general engineering.In 1824, however, Robert Stephenson accepted, perhaps in reaction to an excess of parental control, an invitation by a group of London speculators called the Colombian Mining Association to lead an expedition to South America to use steam power to reopen gold and silver mines. He subsequently visited North America before returning to England in 1827 to rejoin his father as an equal and again take charge of Robert Stephenson \& Co. There he set about altering the design of steam locomotives to improve both their riding and their steam-generating capacity. Lancashire Witch, completed in July 1828, was the first locomotive mounted on steel springs and had twin furnace tubes through the boiler to produce a large heating surface. Later that year Robert Stephenson \& Co. supplied the Stockton \& Darlington Railway with a wagon, mounted for the first time on springs and with outside bearings. It was to be the prototype of the standard British railway wagon. Between April and September 1829 Robert Stephenson built, not without difficulty, a multi-tubular boiler, as suggested by Henry Booth to George Stephenson, and incorporated it into the locomotive Rocket which the three men entered in the Liverpool \& Manchester Railway's Rainhill Trials in October. Rocket, was outstandingly successful and demonstrated that the long-distance steam railway was practicable.Robert Stephenson continued to develop the locomotive. Northumbrian, built in 1830, had for the first time, a smokebox at the front of the boiler and also the firebox built integrally with the rear of the boiler. Then in Planet, built later the same year, he adopted a layout for the working parts used earlier by steam road-coach pioneer Goldsworthy Gurney, placing the cylinders, for the first time, in a nearly horizontal position beneath the smokebox, with the connecting rods driving a cranked axle. He had evolved the definitive form for the steam locomotive.Also in 1830, Robert Stephenson surveyed the London \& Birmingham Railway, which was authorized by Act of Parliament in 1833. Stephenson became Engineer for construction of the 112-mile (180 km) railway, probably at that date the greatest task ever undertaken in of civil engineering. In this he was greatly assisted by G.P.Bidder, who as a child prodigy had been known as "The Calculating Boy", and the two men were to be associated in many subsequent projects. On the London \& Birmingham Railway there were long and deep cuttings to be excavated and difficult tunnels to be bored, notoriously at Kilsby. The line was opened in 1838.In 1837 Stephenson provided facilities for W.F. Cooke to make an experimental electrictelegraph installation at London Euston. The directors of the London \& Birmingham Railway company, however, did not accept his recommendation that they should adopt the electric telegraph and it was left to I.K. Brunel to instigate the first permanent installation, alongside the Great Western Railway. After Cooke formed the Electric Telegraph Company, Stephenson became a shareholder and was Chairman during 1857–8.Earlier, in the 1830s, Robert Stephenson assisted his father in advising on railways in Belgium and came to be increasingly in demand as a consultant. In 1840, however, he was almost ruined financially as a result of the collapse of the Stanhope \& Tyne Rail Road; in return for acting as Engineer-in-Chief he had unwisely accepted shares, with unlimited liability, instead of a fee.During the late 1840s Stephenson's greatest achievements were the design and construction of four great bridges, as part of railways for which he was responsible. The High Level Bridge over the Tyne at Newcastle and the Royal Border Bridge over the Tweed at Berwick were the links needed to complete the East Coast Route from London to Scotland. For the Chester \& Holyhead Railway to cross the Menai Strait, a bridge with spans as long-as 460 ft (140 m) was needed: Stephenson designed them as wrought-iron tubes of rectangular cross-section, through which the trains would pass, and eventually joined the spans together into a tube 1,511 ft (460 m) long from shore to shore. Extensive testing was done beforehand by shipbuilder William Fairbairn to prove the method, and as a preliminary it was first used for a 400 ft (122 m) span bridge at Conway.In 1847 Robert Stephenson was elected MP for Whitby, a position he held until his death, and he was one of the exhibition commissioners for the Great Exhibition of 1851. In the early 1850s he was Engineer-in-Chief for the Norwegian Trunk Railway, the first railway in Norway, and he also built the Alexandria \& Cairo Railway, the first railway in Africa. This included two tubular bridges with the railway running on top of the tubes. The railway was extended to Suez in 1858 and for several years provided a link in the route from Britain to India, until superseded by the Suez Canal, which Stephenson had opposed in Parliament. The greatest of all his tubular bridges was the Victoria Bridge across the River St Lawrence at Montreal: after inspecting the site in 1852 he was appointed Engineer-in-Chief for the bridge, which was 1 1/2 miles (2 km) long and was designed in his London offices. Sadly he, like Brunel, died young from self-imposed overwork, before the bridge was completed in 1859.[br]Principal Honours and DistinctionsFRS 1849. President, Institution of Mechanical Engineers 1849. President, Institution of Civil Engineers 1856. Order of St Olaf (Norway). Order of Leopold (Belgium). Like his father, Robert Stephenson refused a knighthood.Further ReadingL.T.C.Rolt, 1960, George and Robert Stephenson, London: Longman (a good modern biography).J.C.Jeaffreson, 1864, The Life of Robert Stephenson, London: Longman (the standard nine-teenth-century biography).M.R.Bailey, 1979, "Robert Stephenson \& Co. 1823–1829", Transactions of the Newcomen Society 50 (provides details of the early products of that company).J.Kieve, 1973, The Electric Telegraph, Newton Abbot: David \& Charles.PJGR -
82 Computers
The brain has been compared to a digital computer because the neuron, like a switch or valve, either does or does not complete a circuit. But at that point the similarity ends. The switch in the digital computer is constant in its effect, and its effect is large in proportion to the total output of the machine. The effect produced by the neuron varies with its recovery from [the] refractory phase and with its metabolic state. The number of neurons involved in any action runs into millions so that the influence of any one is negligible.... Any cell in the system can be dispensed with.... The brain is an analogical machine, not digital. Analysis of the integrative activities will probably have to be in statistical terms. (Lashley, quoted in Beach, Hebb, Morgan & Nissen, 1960, p. 539)It is essential to realize that a computer is not a mere "number cruncher," or supercalculating arithmetic machine, although this is how computers are commonly regarded by people having no familiarity with artificial intelligence. Computers do not crunch numbers; they manipulate symbols.... Digital computers originally developed with mathematical problems in mind, are in fact general purpose symbol manipulating machines....The terms "computer" and "computation" are themselves unfortunate, in view of their misleading arithmetical connotations. The definition of artificial intelligence previously cited-"the study of intelligence as computation"-does not imply that intelligence is really counting. Intelligence may be defined as the ability creatively to manipulate symbols, or process information, given the requirements of the task in hand. (Boden, 1981, pp. 15, 16-17)The task is to get computers to explain things to themselves, to ask questions about their experiences so as to cause those explanations to be forthcoming, and to be creative in coming up with explanations that have not been previously available. (Schank, 1986, p. 19)In What Computers Can't Do, written in 1969 (2nd edition, 1972), the main objection to AI was the impossibility of using rules to select only those facts about the real world that were relevant in a given situation. The "Introduction" to the paperback edition of the book, published by Harper & Row in 1979, pointed out further that no one had the slightest idea how to represent the common sense understanding possessed even by a four-year-old. (Dreyfus & Dreyfus, 1986, p. 102)A popular myth says that the invention of the computer diminishes our sense of ourselves, because it shows that rational thought is not special to human beings, but can be carried on by a mere machine. It is a short stop from there to the conclusion that intelligence is mechanical, which many people find to be an affront to all that is most precious and singular about their humanness.In fact, the computer, early in its career, was not an instrument of the philistines, but a humanizing influence. It helped to revive an idea that had fallen into disrepute: the idea that the mind is real, that it has an inner structure and a complex organization, and can be understood in scientific terms. For some three decades, until the 1940s, American psychology had lain in the grip of the ice age of behaviorism, which was antimental through and through. During these years, extreme behaviorists banished the study of thought from their agenda. Mind and consciousness, thinking, imagining, planning, solving problems, were dismissed as worthless for anything except speculation. Only the external aspects of behavior, the surface manifestations, were grist for the scientist's mill, because only they could be observed and measured....It is one of the surprising gifts of the computer in the history of ideas that it played a part in giving back to psychology what it had lost, which was nothing less than the mind itself. In particular, there was a revival of interest in how the mind represents the world internally to itself, by means of knowledge structures such as ideas, symbols, images, and inner narratives, all of which had been consigned to the realm of mysticism. (Campbell, 1989, p. 10)[Our artifacts] only have meaning because we give it to them; their intentionality, like that of smoke signals and writing, is essentially borrowed, hence derivative. To put it bluntly: computers themselves don't mean anything by their tokens (any more than books do)-they only mean what we say they do. Genuine understanding, on the other hand, is intentional "in its own right" and not derivatively from something else. (Haugeland, 1981a, pp. 32-33)he debate over the possibility of computer thought will never be won or lost; it will simply cease to be of interest, like the previous debate over man as a clockwork mechanism. (Bolter, 1984, p. 190)t takes us a long time to emotionally digest a new idea. The computer is too big a step, and too recently made, for us to quickly recover our balance and gauge its potential. It's an enormous accelerator, perhaps the greatest one since the plow, twelve thousand years ago. As an intelligence amplifier, it speeds up everything-including itself-and it continually improves because its heart is information or, more plainly, ideas. We can no more calculate its consequences than Babbage could have foreseen antibiotics, the Pill, or space stations.Further, the effects of those ideas are rapidly compounding, because a computer design is itself just a set of ideas. As we get better at manipulating ideas by building ever better computers, we get better at building even better computers-it's an ever-escalating upward spiral. The early nineteenth century, when the computer's story began, is already so far back that it may as well be the Stone Age. (Rawlins, 1997, p. 19)According to weak AI, the principle value of the computer in the study of the mind is that it gives us a very powerful tool. For example, it enables us to formulate and test hypotheses in a more rigorous and precise fashion than before. But according to strong AI the computer is not merely a tool in the study of the mind; rather the appropriately programmed computer really is a mind in the sense that computers given the right programs can be literally said to understand and have other cognitive states. And according to strong AI, because the programmed computer has cognitive states, the programs are not mere tools that enable us to test psychological explanations; rather, the programs are themselves the explanations. (Searle, 1981b, p. 353)What makes people smarter than machines? They certainly are not quicker or more precise. Yet people are far better at perceiving objects in natural scenes and noting their relations, at understanding language and retrieving contextually appropriate information from memory, at making plans and carrying out contextually appropriate actions, and at a wide range of other natural cognitive tasks. People are also far better at learning to do these things more accurately and fluently through processing experience.What is the basis for these differences? One answer, perhaps the classic one we might expect from artificial intelligence, is "software." If we only had the right computer program, the argument goes, we might be able to capture the fluidity and adaptability of human information processing. Certainly this answer is partially correct. There have been great breakthroughs in our understanding of cognition as a result of the development of expressive high-level computer languages and powerful algorithms. However, we do not think that software is the whole story.In our view, people are smarter than today's computers because the brain employs a basic computational architecture that is more suited to deal with a central aspect of the natural information processing tasks that people are so good at.... hese tasks generally require the simultaneous consideration of many pieces of information or constraints. Each constraint may be imperfectly specified and ambiguous, yet each can play a potentially decisive role in determining the outcome of processing. (McClelland, Rumelhart & Hinton, 1986, pp. 3-4)Historical dictionary of quotations in cognitive science > Computers
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