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The world “à la carte”
- Introduction to cartography
- The map of the world: from circle to sphere
- From sky to screen
- Cartography in the 3rd millennium
The map of the world: from circle to sphere
3,000 years ago the Polynesians in the Marshall Islands made models out of sea-shells and bits of wood. On these early “maps”, the sea-shells represented islands and the sticks of wood showed the directions. Since then, maps have developed in tandem with our techniques and beliefs.
Birth of the modern-day map
The map as we know it was invented by the mathematicians and philosophers of Ancient Greece. In the 5th century BC, Pythagoras already knew the Earth was spherical. Towards the end of the 1st century AD, Ptolemy produced the first known flat map of the surface of the earth.
In the Middle Ages, the Earth was thought to be a flat disc, as described in the Bible. Any unknown territories were considered to be inhabited by monsters and chimera. Mediaeval maps are fabulous works of art, but mathematical anomalies.
As sea-faring voyages between the continents increased, navigators gradually made people realise that the Earth is round.
In the 16th century, Gerhard Kremer, known as Mercator, invented the planisphere, or in other words, a map on which true courses are represented by straight lines... laying the foundations of the modern-day map.
The map of France
There have always been two kinds of map: military and civilian. For the armed forces, a map is strategic, therefore secret and small-scale. For civil engineers, it must be made public and drawn to the largest possible scale to be used for designing civilian infrastructure.
When Colbert created the French Academy of Science in 1666, he favoured the development of a branch of cartography specifically for use in major public works projects. The first maps of France were drawn by Jean Picard and four members of a single family: the Cassinis.
These maps are based on the principle of “triangulation”, i.e. dividing the territory into triangles, with measurements being taken of the distance from one church spire to the next.
At the beginning of the XIX century, the first geological survey maps began to appear and continued to be produced until 1945. For a long time these served as “topographic bases”, to be replaced in the latter half of the XX century by the 1 : 25 000 map. The arrival of aerial photography, which was first attempted in 1921, and the spread of micro-computing, were to change everything.
Projections
A map is a flat portrayal of the earth, which is a sphere.
A projection is used to formalise this representation.
