Mapping: A Comprehensive Overview of the History, Science, Techniques and Modern Applications of Cartography

The purpose of a map is to express graphically the relations of points and features on the earth’s surface to each other. These are determined by distance and direction.

In early times ‘distance’ might be expressed in units of time, or lineal measures —so many hours’ march or days’ journey by river, and these might vary on the same map according to the nature of the country.

The other element is direction, but for the ordinary traveller, whose main concern was “‘Where do I go from here, and how far away is it?” the accurate representation of direction was not of primary importance.

Partly for this reason, written itineraries for a long time rivalled maps, and throughout the centuries from the Roman road map to the thirteenth-century itinerary from London to Rome of Matthew Paris and even to the Underground and similar ‘maps’ of today, no attempt is made to show true direction.

Similarly, conspicuous landmarks along a route were at first indicated by signs, realistic or conventional, and varied in size to indicate their importance.

Clearly the conventions employed varied with the purpose of the map, and also from place to place, so that in studying early maps the first essential is to understand the particular convention employed.

History and Development of Cartography

The history of cartography is largely that of the increase in the accuracy with which these elements of distance and direction are determined and in the comprehensiveness of the map content.

In this development cartography has called in other sciences to its aid.

Distances were measured with increasing accuracy ‘on the ground’; then it was found that by applying trigonometrical principles it was unnecessary to measure every requisite distance directly, though this method required the much more accurate measurement of a number of short lines, or bases.

Similarly, instead of determining direction by observing the position of a shadow at midday, or of a constellation in much more accurate measurement of a number of short lines, or bases.

Similarly, instead of determining direction by observing the position of a shadow at midday, or of a constellation in the night sky, or even of a steady wind, use was made of terrestrial magnetism through the magnetic compass, and instruments were evolved which enabled horizontal angles to be measured with great accuracy.

Astronomy and Projections

Meanwhile the astronomers showed that the earth is spherical, and that the position of any place on its surface could be expressed by its angular distances from the Equator (latitude) and a prime meridian (longitude), though for many centuries an accurate and practical method of finding longitude baffled the scientists.

The application of these astronomical conceptions, and the extension of the knowledge of the world through exploration and intercourse, encouraged attempts to map the known world — but this introduced another problem: how to map a spherical surface on a flat sheet.

The mathematician came to the rescue again—with his system of projections, by which some, but not all, spatial properties of the earth’s surface can be preserved on a single map.

Geodesy and Triangulation

Then the astronomers discovered that the earth is not a perfect sphere, but is flattened slightly at the Poles; this introduced further refinements, such as the conception of geodetic as opposed to astronomical latitudes, into the mapping of large areas, and great lines of triangulation were run north and south across the continents to determine the true ‘figure of the earth’, and to provide bases for their accurate mapping.

New Users and Techniques

Meanwhile, increasing demands were being made on the map maker. The traveller or the merchant ceased to be the sole user of maps.

The soldier, especially after the introduction of artillery, and the problems of range, field of fire, and dead ground which it raised, demanded an accurate representation of the surface features, in place of the earlier conventional or pictorial delineation, and a solution in any degree satisfactory was not reached until the contour was invented.

This again adds to the task of the surveyor who must run lines of levels and sometimes go to the extent of pegging out the contour lines on the ground.

Scientific Applications and Distributions

Then the archaeologist, the historian, and much later, the modern geographer had their own special requirements, and in co-operation with them the cartographer must evolve methods of mapping all kinds of ‘distributions’, from geological strata and dolmens, climatic regimes and plant associations, to land use and ‘urban spread’.

It is the present widespread recognition of the value of the map in the coordination and interpretation of phenomena in many sciences that has led to what may truly be called a modern renaissance of cartography.

Continuity, Setbacks and Limitations

It would be misleading to represent the stages summarily sketched above as being either continuous or consecutive.

There have been periods of retrogression or stagnation, broken by others of rapid development, during which outmoded ideas have held their place beside the new.

Again, cartographers have constantly realized the theoretical basis for progress, but have had to wait for technical improvement in their instruments before they could apply their new ideas.

Since the easiest way to make a map is to copy an old one, and considerable capital has often been locked up in printing plates or stock, map publishers have often been resistant to new ideas.

Consequently, maps must never be accepted uncritically as evidence of contemporary knowledge and technique.

Contributors and Professions Involved

In studying cartographical history, the various classes of individuals who have contributed to the map as it reaches the public must be clearly differentiated.

The explorer, the topographical surveyor and the geodesist, with their counterparts on the seas, the navigator and the hydrographical surveyor, provide the data; the compiler, computer, and draughtsman work them up to the best of their ability; and finally, with printed maps and charts, the engraver or printer has his part in determining the character of the finished map.

Historical Cartography and Documentary Value

Further, in earlier centuries, when a considerable speculative element entered into ideas on the distribution and configuration of land masses, the cosmosgrapher often interpreted or applied the results obtained by explorers to fit into preconceived opinions.

Professor E. G. R. Taylor has also warned the student against the booksellers and engravers, “who copied and compiled what they wanted quite uncritically, using any old maps and plates that came to hand”.

Clearly the maps, many thousands in number, which have come down to us today, are the results of much human work and thought.

They constitute therefore an invaluable record for the student of man’s past. It is above all this aspect with the complex problems, scientific, historical and human, which it raises, that makes the study of historical cartography so fascinating and so instructive.

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