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American Shores Maps of the Middle Atlantic Region to 1850 The New York Public Library
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Overview Basics of Maps Maps Through History Geographical Areas

Definitions: Basics for Looking at Maps

A map can be defined as a visual representation of a given location. Maps, both decorative and functional, have been made of the earth's surface, the moon, a planet, the ocean floor, etc. A chart, a type of map, is used specifically for navigation; charts usually contain shoreline details, depths and shoals, and other navigational aids. Sometimes charts are contained in a pilot, a bound collection of written nautical directions.

This section includes basic information about maps and the meanings of some of the more common elements found on them.
Note: For a visual guide to these definitions, please refer to this illustration.

Orientation and distance are the two most important elements of a map. While on modern maps a north arrow indicates direction, antique maps often have a compass rose or wind rose to show the four cardinal directions: north, east, south, and west. Wind roses sometimes have solid and dashed lines, called rhumblines, radiating out across the charts. These lines add a distinctive diagonal grid to many of the early maps and charts.

Distance on a map can be determined by the scale, which is shown by one or more ruled lines that mark off miles or other lengths of measure. On early maps the scale indicator is sometimes decorated with a pair of dividers, an instrument used to measure distance on maps and charts. Many maps have a grid of latitude, which measures distance in degrees north and south of the equator, and longitude, which measures distance in degrees east and west of a prime meridian. The numbers of this grid, indicating location on the earth's surface, appear at the borders of the map. Greenwich, England, is often designated the prime meridian locale on world maps today. However, many early maps of America have Philadelphia, New York or Washington D.C. as their prime meridian cities.

On old maps, the cartouche, a highly decorative frame, contains such information as the title of the map and the name of the mapmaker, or author of the map (sometimes called a cartographer). Depictions of world ports, inhabitants in ethnic dress, and regional land features were sometimes provided for additional reference. A coat of arms signified ownership of the land described.

Older maps are often quite decorative and colorful. Decoration might be as practical as a border, lines of latitude and longitude, or the directional rhumblines radiating from a compass rose. A cartouche might be heavily decorated with flowers, navigational instruments, or coats of arms. More lively imagery includes indigenous animals and plants, people, housing types, gold, and tobacco. The images on maps can be as important as geography, since they inform viewers back home of unusual flora and fauna, of peoples to "convert" or of opportunities for gaining personal wealth.

Detailed coastal charts, called portolans, are among the earliest known maps. Developed in the Mediterranean area, they date from the 14th century, if not earlier. They are much more accurate than the land maps of the time, which tended to be symbolic in nature, reflecting biblical descriptions or Classical ideals about the Earth and its form, rather than geographic representations.

For more information on portolans, see the University of Minnesota, James Ford Bell Library site

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