The History of Cartography

A map is such a familiar object that it is easy to forget what a strange and remarkable thing it is. To draw a map is to shrink the world onto a flat surface and to decide what to leave in and what to leave out. Every map is therefore a kind of argument about which features of a place matter most. The history of mapmaking, or cartography, is not simply a record of increasing accuracy. It is also a history of changing beliefs about the shape of the world, the purposes maps were meant to serve and the people who made and used them.

The earliest surviving maps are thousands of years old and look nothing like the maps of today. Some of the oldest were scratched onto clay tablets and show small local areas, such as a city and the fields around it. Others were less concerned with geography than with belief, placing a sacred city or a homeland at the centre of the world and arranging everything else around it. These maps were not meant to guide a traveller from one place to another so much as to express how their makers understood their own position in the universe. Distance and direction, as a modern reader would measure them, were often far less important than symbolic meaning.

A great step forward came with the scholars of the ancient Mediterranean world, who began to think about the Earth in mathematical terms. They recognised that the world was a sphere and worked out ways of describing any location by two numbers, giving its position north or south and east or west. This idea, the ancestor of modern latitude and longitude, made it possible in principle to place every point on a single consistent grid. One geographer of the ancient world even compiled a vast list of places with their coordinates, together with instructions for drawing them, so that a map could be reconstructed by anyone who followed his method. Much of this knowledge, however, was lost or neglected for centuries in some regions before being recovered later.

During the medieval period, mapmaking flourished in several parts of the world. Scholars in the Islamic world preserved and extended the mathematical geography of the ancient Mediterranean, producing detailed and comparatively accurate maps and gathering information from travellers who journeyed across vast distances. In Europe, meanwhile, many maps of the time were designed less for navigation than for teaching and contemplation, combining geography with religious and historical ideas. Sailors, by contrast, relied on a different kind of chart that recorded coastlines, harbours and the compass bearings between ports, tools of great practical value to those who made their living on the sea.

The age of long ocean voyages transformed cartography. As ships sailed farther and returned with reports of unfamiliar coasts, mapmakers scrambled to incorporate the new discoveries, and maps became prized and sometimes closely guarded sources of commercial and political power. This period also forced cartographers to confront an old and stubborn problem: how to represent the curved surface of a globe on a flat sheet of paper. Any such representation must distort something, whether shapes, sizes, distances or directions, and no flat map can preserve them all at once. Different solutions, known as projections, were devised to suit different purposes. One famous projection made it easy for sailors to plot a straight course of constant compass bearing, but it did so at the cost of greatly exaggerating the size of regions far from the equator, a distortion that has shaped popular impressions of the world ever since.

For centuries the accuracy of maps was limited by the difficulty of fixing position precisely, especially at sea. Determining how far north or south a ship lay was relatively straightforward, but measuring how far east or west it had travelled long defeated navigators, leading to errors that could wreck vessels and cost lives. The eventual development of reliable methods for finding this second measurement was a milestone that allowed maps of the oceans and coastlines to be drawn with new confidence. Surveying the land, too, grew steadily more systematic, as teams of surveyors measured their way across whole countries to produce maps of unprecedented detail.

Today the tradition continues in forms its early practitioners could scarcely have imagined. Satellites orbiting the Earth gather images and measurements of the whole planet, and digital maps on handheld devices can locate their users to within a few metres and redraw themselves instantly as people move. Yet the essential act remains what it always was: selecting from the endless complexity of the real world a limited set of features and arranging them to tell a useful story. In that sense the humble map still carries out the same task it performed on its earliest clay tablets, even as the tools for making it have been transformed beyond recognition.