A regular reader of this blog (thank you) suggested I write on the topic of directional orientation in maps. Why are most maps oriented to the north? How did this practice originate? Is it necessary? Is it universal? The concept of a consistent northward orientation in all maps is neither as standardized nor as universal as it might seem at first glance. Even in modern times, it is more practical for many maps to have orientations other than north. The standard map of New York City for example, a variant of which is the classic New York Subway map, is commonly oriented to the northeast. In some non-western cultures with highly developed cartographic traditions, such as Japan, directional orientation is often not even a factor – but we will return to this at a later point.
In the west, if it can be called that, the tradition of orienting maps to the north began, as did so many things cartographic, with the 5th century Alexandrian geographer Claudius Ptolemy. Ptolemy’s work, the Geographica, is considered the first known geography. While the Geographica as it has come down to us today has no maps in it, it does contain detailed instructions for the construction of a map. These include a well laid out coordinate system and considerable geographic description.The world as it was known to Ptolemy would have been centered on a relatively narrow latitudinal swath of land focused around the Mediterranean. The known lands at that time would have extended from the Strait of Gibraltar eastward as far as India. The southern lands beyond the Sahara and most of northern Europe and Asia were, for all intent and purposes, unknown. Thus, in order for Ptolemy to fit his map on a long narrow scroll, it would have been oriented to either the north or the south. Some scholars argue that this alone was sufficient motivation for Ptolemy to orient his map to the north. However, upon a closer examination of Ptolemy’s work, we can see that the real reasons behind his choices are more complex.
Ptolemy was very much aware that the world was spherical and that his home in Alexandria was in the Northern Hemisphere. With this knowledge in hand Ptolemy went about assembling his coordinate system. Ptolemy realized that for his coordinate system to be consistent, he needed a mathematical formula that would enable him to map the globular world on a flat surface – a projection. While Ptolemy did not invent the idea of a projection system, he did refine it considerably. Ptolemy’s intention was that his projection “above all the semblance of the spherical surface be retained” and that “it would be well to keep lines representing the meridians straight”. What he came up with is today referred to as a conical projection, with all longitudinal lines meeting at the north pole and radiating outward towards the equator, at which point they again radiate inwards, this time towards the South Pole.
While Ptolemy could have, in theory, calculated his meridians to meet at any point on the globe, the north pole was the most practical choice. The reason behind this is as follows. First, the Ptolemaic world was a band focused on the central part of the northern hemisphere. It did not extend exceptionally far either north or south. Since the meridians on his projection converged as the map went further north, the room for detail decreased – which was fine, since he didn’t know what was there anyway – leaving the plenty of room for detail in the known central parts of the maps. Second, the Ptolemaic world was divided into various climatic zones, the inhospitable frigid zones (near the poles), the hospitable temperate zones (the northern of which occupied much of the known world), and the inhospitable torrid zone on either side of the equator. With such a zonal layout intact, Ptolemy knew his focus must be on the habitable zones of the northern hemisphere and consequently he designed his projection to reflect this. Third, as an astronomer, Ptolemy would have made regular celestial observations and therefore been familiar with the movements of the heavens around the fixed point of Polaris, the North Star. Therefore, as a matter of making his projection mathematically simpler, of encapsulating his known world, and of aligning the globe with the celestial spheres, the choice of a northward orientation would have been obvious.With the fall of the Roman Empire and the collapse of European civilization in to the middle ages, Ptolemy was, for all intent in purposes, forgotten. This world map, known as the Beatus Map, dates to c. 1050 and is one of the oldest surviving medieval maps. It is also a beautiful example of the mapping conventions that developed during this period. This maps offers a religious view of the cosmos and, though interesting on many levels, has little of the cartographic sophistication of Ptolemy’s Geographica. The map depicts the world as a flat disk centered on Jerusalem. Most medieval scholars believed that the Garden of Eden lay at the extreme eastern end of the world. Being closely associated with heaven, Eden the Earthly Paradise was naturally placed at the top of the map. Most other maps of the period followed suit. It was not until the Renaissance that the works of Ptolemy were rediscovered. With their coordinate system and scientific approach, Ptolemy’s maps were quickly recognized by Renaissance scholars as superior to most contemporary material. With the development of printing, Ptolemy’s maps were mass produced and, relatively speaking, widely available. These maps re-established the convention of a northward orientation. It is also around this time that the Great Age of Exploration truly gets underway and maps suddenly were given a new purpose – navigation. Early sailors tended to either hug the coast or, when entering the open sea, travel in a straight line along a directional path. Consequently, what navigators need was a map that presented the entire world on a flat plane such that any two points could be connected with a straight line. In this way, a ship need only be oriented in the correct direction, and after a period of sailing, should, in theory, arrive at the desired destination. Enter the Mercator Projection. Mercator’s projection was essentially a navigational tool that sacrificed proportion for the ability to accurately connect all points with straight lines. These lines, which appear on most navigational maps, are called rhumb lines. The use of Mercator Projections, rhumb lines, and the compass for navigation solidified the convention established by Ptolemy. Even so, not all maps were oriented to the north. Mapmakers regularly, though not frequently, oriented maps in other directions. Sometimes the decision to use an alternate orientation was based upon the need to fit a region of a certain form onto and appropriately sized sheet. Maps of the Holy Land, for example, were frequently oriented to the East. Several important maps of North America, including Blaeu’s Nova Belgica et Anglia Nova, also use unusual orientations. It is not until the 19th century that almost all new maps being made were given a northward orientation. All the above applies to European cartography. Mapmaking in other parts of the world, like Japan for example, did not use an established directional orientation. Many Japanese maps from the Edo Period, what might be considered the Golden Era of Japanese Cartography, radiate outward from the center, so that to read the map, you would simply orient it to the direction you are facing. This has some practical advantages for getting around but was most useful only on smaller scale maps and city plans. In the Meiji period (late 19th century), European cartographic norms began to exert an influence on traditional Japanese Cartography. By the turn of the century, most Japanese maps had adopted a northerly orientation.
To recap, the convention of orienting maps to the north comes down to us from Ptolemy, for whom it was a practical choice given the style in which his maps were made, the extent of the world he attempted to cover, and the nature of his projection. While briefly abandoned in the middle ages, the northerly convention was re-established during the renaissance and reaffirmed with the advent of navigational cartography in the 16th century.
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