124 research outputs found

    Maps for Africa

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    [Introduction] Opening address by Oakley West at exhibition: Maps: Knowledge and Power - A Teaching Exhibition at the Albany Museum, November 1992. Maps, like art, reflect man's perception of the world in which he lives. Often they are coloured both by the known and unknown, by fact and fancy, myth and mystery. Maps are not just merely bits of paper. They are, and have been, important instruments in conquest and empire building. They reflect not only the perceived glory of war and occupation, but survival under siege, the protection or defence of people, property and resources, and, believe it or not, the accidental inheritance of territory, like India. Maps reflect the build-up of nations bent on expansion, resulting in the dreadful years of trench warfare in 1914 - 1918. And who of us can honestly admit that we knew exactly where Kuwait was before that conflict began? Thus in many cases lands were often first claimed on paper before they were effectively occupied. It has been said that no place is truly discovered until it has been mapped and as much as guns and warships, they have played significant roles in manifesting the realities of conquest and empire building. Maps are storehouses of knowledge and information and often it is in that very knowledge that lies the power to conquer, control, defend, divide or develop, to govern or administer or even mislead or misinform. This exhibition attempts to trace almost 2 000 years of cartography. It starts with the great insights of Claudius Ptolomy and his Geographia, continues through the retrogressive perceptions of the Church fathers and their decrees that Jerusalem was the centre of the world, to the perception of a flat Earth and a rather whimsical look at modern "upside-down" cartography which has proved to be only 300 years late in its conception. One can explore the opening up of the dark continent of Africa with its myths and mysteries, the source of the Nile, Mountains of the Moon and the mythical kingdom of Monomatapa. One can "see" the gradual growth of knowledge as first the coasts and later the interior was discovered and made known by men like Diaz, Da Gama, Livingstone, Stanley and Andersson. The discoveries of these explorers were recorded in the great maps of cartographers like John Arrowsmith and Henry Hall, the former incidentally never ever having visited Africa. A quantum leap takes us to some of the newest techniques, the satellite image, which still reflects the historical heritage in the shapes and patterns formed, in what has become known as Settler Country, from as early as the 1800s. By these images one is still able to appreciate the ravages of drought, overgrazing and perhaps the mismanagement of natural resources. Maps show us a different Grahamstown, a Graham's Town lit by gaslamp light. They help us to "see" prison gangs building the Queen's Road to Fort Beaufort, or appreciate the scramble for river frontage farming land. We see the early conceptualization of a harbour scheme at the mouth of the Kowie River, dreamed of by those intent on opening up a gateway to the Eastern Frontier through its wide waters. (A scheme, incidentally, which finally found a different, but nonetheless effective, realisation in the Marina built in the 1990s). Dreams were dreamed of a wide-spread colonial administration, though not without its nostalgic overtones: King William's Town would be the principal town in the county of Middlesex and Komga that of the county Cambridge in British Kaffraria! One can trace in maps the expanding horizons of the colonial powers as they appropriated land in the name of civilisation. As the church and the courts moved in to replace tribal customs and laws, maps reflected the more tangible results of expansion - telegraph, road and rail networks, as well as the more abstract and intangible - the spread of violence. On the other hand, we can follow the development of a great city, the city of London, though almost 400 years, witnessing the growth of its urban sprawl, the depiction of the famous bridges over. the Thames and who could not but be thrilled by the panoramic sweep of London from the Houses of Parliament through St Pauls to the sailing ship harbour, cartography par excellence which evidences the birth of a rail system with engines looking distinctly more akin to Stevenson's rocket than the locomotives we are used to seeing. An exceptionally fine relief model of the Western and Southern Cape coastal area serves to highlight the unending struggle of cartographers to portray that troublesome third dimension, height, on flat pieces of paper. Such struggles are revealed both in maps of topographic landscape as well as the urban complex - some successful, some not so. Finally, the exhibition touches lightly on the wonders of satellite imagery and the coming of the computer to cartography, as in all things. An attempt is made to explain in simple terms the art, science and technology of the cartographer in the production of the multicoloured maps we are all so familiar with

    Children's daily travel to school in Johannesburg-Soweto, South Africa: geography and school choice in the Birth to Twenty cohort study

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    This paper has two aims: to explore approaches to the measurement of children’s daily travel to school in a context of limited geospatial data availability, and to provide data regarding school choice and distance travelled to school in Soweto-Johannesburg, South Africa. The paper makes use of data from the Birth to Twenty cohort study (n=1428) to explore three different approaches to estimating school choice and travel to school. Firstly, straight-line distance between home and school is calculated. Secondly, census geography is used to determine whether a child's home and school fall in the same area. Thirdly, distance data are used to determine whether a child attends the nearest school. Each of these approaches highlights a different aspect of mobility, and all provide valuable data. Overall, primary school aged children in Soweto-Johannesburg are shown to be travelling substantial distances to school on a daily basis. Over a third travel more than 3km, one-way, to school, 60% attend schools outside of the suburb in which they live, and only 18% attend their nearest school. These data provide evidence for high levels of school choice in Johannesburg-Soweto, and that families and children are making substantial investments in pursuit of high quality educational opportunities. Additionally, these data suggest that two patterns of school choice are evident: one pattern involving travel of substantial distances and requiring a higher level of financial investment, and a second pattern, involving choice between more local schools, requiring less travel and a more limited financial investment

    Using satellites to monitor Severn Bridge structure, UK

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    The Severn Bridge is a large UK suspension bridge. In 2010, a series of field surveys was commissioned to monitor the magnitude and frequencies of the bridge’s movements, through attaching nine dual-frequency survey grade global navigation satellite system receivers on the bridge and two reference satellite receivers adjacent to the structure. The satellite antenna locations and configuration allow the movements of the north cable to be analysed at four locations, as well as the differential movements of the two suspension cables to each other. In addition, this configuration allows the movements of the tops of the towers to be compared to the cables’ movements, as well as with each other. All in all, this allowed the relative movements of the various locations on the bridge’s suspension cables and tower tops to be compared to each other, at a rate of up to 20 Hz. Overall, some 3 days of raw code and carrier phase satellite data were gathered. During these sessions, normal traffic loading was experienced. This paper describes the survey, presents a selection of the key results and draws conclusions about the effective use of satellite positioning systems to enhance structural health monitoring.The Highways Agency, Severn River Crossing plc and Mott MacDonal
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