Maps and the Ideas they Express

Meanwhile, Europe was awakening from the long period called the Middle Ages, between classical antiquity and the Renaissance. A map that expresses medieval ideas, while heralding the new era, is the T–O map from Isidore of Seville's earlier manuscript Etymologiarum. (These letters refer to water bodies: the Mediterranean Sea and the Don and the Nile rivers forming the "T" within the "O," or circumfluent Ocean on these largely landcovered, east-oriented world maps.) It was published in 1472 to become the first map printed in Europe (Fig. 6). Following this, the printed map gradually replaced the manuscript map for most purposes in Europe and elsewhere.

A new approach to mapmaking arose in Europe, building upon earlier cartographic models. Greek texts of Ptolemy's Geographia reached Italy from Byzantium c. 1410, and were translated into Latin. Soon maps were made from these instructions, and it became the business of European cartographers to improve upon this late-classical geography, as for example in the 1427 manuscript map of Scandinavia by the Dane, Claudius Clavus. Two major developments in Europe now influenced cartography, as indeed other aspects of life: the independent invention of printing in Europe, and the spread of Europeans around the globe. The (nearly) exactly repeatable representation made possible by the printing press eventually led to a wider dissemination of geographical knowledge, while the contemporaneous discovery of half of the coasts of the world and many islands, in the fifteenth and sixteenth centuries, provided new source material for European cartographers.

The first to utilize these sources and techniques were the mapmakers of the nearly land-locked states of present-day Italy and Germany: The Bologna Ptolemy, 1477, twenty-six sheets printed from engraved copper plates; and the Ulm Ptolemy, 1486, incorporating Clavus's amendments on a single wood-cut print, are examples of this cartography. After a period of coexistence, copper-plate engraving prevailed over the wood-cut method, and the Low Countries (present Netherlands, Belgium, and the lower Rhineland) became the focus of the new global cartography. The near eclipse of woodcut printing led to the virtual abandonment of color map printing in Europe for three centuries. Copper-plate engraving does not lend itself so well to color printing as does the woodblock method, of which a few examples of colored prints from the Renaissance are extant.

With their explorations along the western shores of Africa, the Portuguese from 1420 on provided a rich source of new coastal and insular information. Likewise, the Spanish provided information about the Americas, following the discoveries by Columbus, 1492–1504, and others. Although attempts were made to keep this intelligence secret, it soon became known through the dissemination of data published mostly by the other Europeans in the form of printed maps and atlases. As indicated, the cartographers of the Low Countries eventually came to dominate this lucrative trade during the sixteenth and seventeenth centuries. Although marine charts were the first products, soon other map subjects were covered: inland provinces, urban centers especially in Europe, historical topics, biblical events, and so forth.

Figure 4. Hereford Mappa Mundi, c. 1300 C.E. Drawing on vellum. THE DEAN AND CHAPTER OF HEREFORD AND THE HEREFORD MAPPA MUNDI TRUST

Several individuals and families were involved in this map and atlas production: Abraham Ortelius, Theatrum orbis terrarum (1570, and later, in several languages); Gerhard Mercator, with the map projection that bears his name (1569) and Atlas (1595); Georg Braun (Joris Bruin) and Frans Hogenberg, Civitates orbis terrarum (1572, and later); Lucas Janszoon Waghenaer, De Spieghel der Zeevaerdt (1584), translated into English as the Mariner's Mirrour (1588); and others. There were Figure 5. Early map of China with rectangular grid, c. 1137. Carved on stone. REPRINTED WITH THE PERMISSION OF CAMBRIDGE UNIVERSITY PRESS Figure 6. T-O world map from Etymologiarum (1472) by Isidore of Seville. BY PERMISSION OF THE BRITISH LIBRARY, IB.5438 many followers and imitators of these pioneers, and some Renaissance maps and atlases, many hand-colored prints from monotone engraved plates, became more decorative than innovative, but are prized as collector's items to this day. The greatest cartographer of the sixteenth century was Mercator, whose projection was one of a dozen new ways of expressing Figure 7. Mercator Projection for world map, 1569. the graticule (lines of latitude and longitude) invented during this period. A few of these are still in use today, including the Mercator Projection (Fig. 7), on which any straight line is a correct compass direction and thus of great value to navigators, but which has been much misused for mapping Earth distributions, where correct size is important. The English mathematician Edward Wright provided an explication and details for construction of this projection (not given by Mercator) and it was popularized by Robert Dudley and others in the seventeenth century.

Early modern academies and innovative methods of representation.

The Italian astronomer Giovanni Domenico Cassini (1625–1712) initiated another new approach to map-making when he accepted an invitation to the then recently founded Paris Observatory. Both that institution, and the observatory at Greenwich, England, were established in the middle of the seventeenth century through the sponsorship of the also newly founded Académie Royale des Sciences in France, and of the Royal Society of London, respectively. These academies were to play an important role in the development of a more scientific cartography, which characterized the mapping of the Earth during the following three centuries.

In a period of over one hundred years, four generations of the Cassini family supervised the accurate topographic mapping of France in multiple sheets. The first step was to measure the length of a degree of latitude with great accuracy, which was completed in 1670. From this base, a network of triangles was eventually extended across the whole country. The work of filling in detail, covering more than 180 sheets, was not finished until 1793. One unexpected result of this work, and measurements by French surveying expeditions at the Equator, and at high northern latitudes of Europe, was confirmation of the hypothesis of Isaac Newton that the Earth is an oblate (polar-flattened) spheroid; not a prolate spheroid, or perfect sphere, as proposed earlier. Shortly, detailed topographic surveys were undertaken in other European countries and in their overseas possessions. Thus India, under the British, Figure 8. Lunar map by Galileo from Sidereus nuncius (1610). became one of the best surveyed large countries at a fairly early date.

Other directions in which cartography developed in the seventeenth and eighteenth centuries include: astronomical mapping; thematic or special-subject mapping of Earth; the development of new representational techniques; and innovative map projections. The invention of the telescope led to the mapping of the Moon; Galileo's sketch map of 1610 was the bellwether of a large number of other lunar maps (Fig. 8). Other astronomers who made contributions to this new field of mapping include: Franciscus Fontana, Johannes Hevelius, Giambattista Riccioli, and Giovanni Demonico Cassini. Through these scientists the mapping of the side of the Moon visible from Earth was improved and features named. Thematic mapping had existed before the scientific revolution of the seventeenth century, but a new cartography developed in this period, based on instrumental surveys: maps of wind directions and of magnetism by Edmond Halley; and isobathic (depth) mapping by Nicholas Cruquius are examples of the new scientific cartography (Fig. 9). Innovative methods of representation related to these developments included the isobath and the isogonic line, two of the earliest forms of the contour method, which was so greatly expanded in the following centuries that now there are some fifty types of isoline in use. The development of new and useful map projections also mark this period. A number of mathematicians were involved in the invention of different ways of representing the Earth on a grid or graticule (lines of latitude and longitude). In this regard particularly important were the equal-area projections of the German-Swiss Johann Lambert (1728–1777), arguably the most prolific inventor of map projections of all time. These advances continued as new overseas areas were "discovered" and mapped, facilitated by improved ships, and the solution of the problem of determining longitude at sea. The resolution of this age-old enigma in the late eighteenth century was owing to the invention of the marine chronometer, one of several devices that profoundly affected navigation and cartography.