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At its simplest, cartography is the art and science of drawing charts and maps. It is a science because it requires scrupulous observation and recording of information and location, but it is also an art because the selection and presentation of the information in symbolic form involves aesthetic judgement. The nature of the map is guided by its purpose, which ranges from specific confidential information for limited circulation to general purpose series maps or atlases available to the public. Usually, presentation is guided by the need for accuracy, clarity and relevance to the purpose of the map, but sometimes maps are used for fictional or propaganda purposes.
Maps are known from very early societies, for example, recording plots of land on the Babylonian flood plain or showing distances and way stations on the Roman road network. Even the simplest societies had need for maps and used sketches drawn on the ground, wood or pieces of cloth, as well as stories or songs that carried information about other places and how to get there. The highpoint of cartography in the ancient world was Ptolemy\'s Geographia (2nd century  CE): this included discussions of the principles of map making, details of several map projections and latitude and longitude of 8,000 places, as well as world maps. Unfortunately, this was later lost to Europe (though known to the Arabs) and for a thousand years maps of large areas were extremely distorted in shape and scale, perhaps most notably in the medieval maps showing a world centred on Jerusalem. Such maps were influenced by abstract ideas about the proper balance of continents and seas, and also suggested that the inhabitants of distant countries were less enlightened than those of Europe and the Mediterranean. Maps used for more practical purposes, especially sea charts, were more advanced and ultimately spurred a revolution in cartography.
The first major impetus in the development of cartography was provided by the European ‘Voyages of Discovery’ in the 15th and 16th centuries. Cartography was inspired by the rediscovery of Ptolemy and new information from navigation, as the use of compass, log, sextant and chronometer allowed both ships and coasts to be located with ever greater accuracy on the globe. Cartographers used the new printing technology to produce atlases which were works of art, but they also developed new map projections and it was no coincidence that the most famous, that of Mercator, equated a straight line on the map with a constant compass course. Even the errors of the past contributed: Columbus was encouraged to seek a western route to China because he was misled by maps based on Ptolemy and hence on Posidonius\' 7,000 mile underestimate of the world\'s circumference. By the 18th century most of the world\'s coasts were mapped, but many inland areas remained terra incognita.
The major step forward in land surveying was the use of trigonometry to locate places by measuring angles rather than distances. This greatly increased the speed and accuracy of survey, and was first used by private map makers, such as Saxton, who produced the world\'s first national atlas in 1579. Two centuries later, the outstanding quality of the 182 sheets of the Cassini maps of France made the British army realize the importance of accurate mapping and led to the establishment of the Ordnance Survey to map the whole of Britain and then the Empire. During this century, subsequent advances were also pioneered by the military, from air photographs to satellites. The routine television weather report shows how dramatically cartography has progressed, with the ability to use satellite, radar and a global network of recording stations to provide the data for computer-generated maps of current and predicted weather conditions. The move from maps of isobars and fronts to maps of wind arrows, cloud cover and temperature zones shows the importance of presentation in making maps communicate with their users.
As we approach the end of the millennium, large amounts of information are available about many parts of the world—far more than can be included in a single map. Cartographers are now engaged in developing methods of linking information to location in ways which allow users to specify their own maps: these are Geographical Information Systems. PS |
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