INTRODUCTION 



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, w^hose 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 land- 

 marks 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 con- 

 vention employed. 



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 



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