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Mapping our Globe - Mercator's Map
Gerardus Mercator invented this map in 1567. It was an excellent map in the sixteenth century when the main use of maps was for navigation by sailors to guide their ships to distant lands. 'Mercator' is still the only map which gives true bearings - so it is still very useful for navigation.
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| Mercator's Map of the World (1569) |
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The Mercator map keeps the lines of longitude parallel with each other - unlike those shown on the globe. Lines of latitude are spaced further and further apart towards the poles. This has the effect of:
- keeping the shape of any small area of the world fairly accurate
- exaggerating the size of lands in the higher latitudes - especially evident in the northern hemisphere.
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No-one knows why the Mercator map became so widely used in schools. Educationalists have been denouncing its use since at least 1910. It has come under particular criticism for exaggerating the importance of northern lands compared with Third World countries in tropical latitudes.
Compare the apparent size of Greenland and South America on Mercator, compared with an equal area projection.
New technology may have given Mercator maps a new lease of life. Many computer packages work on a grid of vertical and horizontal lines. Non-geographers may assume that the vertical lines on the computer can be used for lines of longitude. But on the globe, the lines of longitude come closer and closer to each other as you approach the pole. If vertical lines are used for likes of longitude, the effect will be either huge enlargement of the northern lands (as on the Mercator map) or excessive distortion of shapes.
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