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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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