Babylonians, for example, made maps of their cities and, like a number of early
civilizations, also studied the stars. Astronomical drawings and charts were also
an important ancient application of cartography, often used not only for scientific
applications but for religious purposes as well. The Babylonians may have
produced the first map of the “world,” at least the world as they knew it, in the
Imago Mundi, a geographical depiction of the Tigris-Euphrates river valley and
its environs.
The ancient Greeks were the first culture to develop scientific techniques for
making accurate maps. Two Greek scholars have a particular importance in the
history of cartography: Eratosthenes and Ptolemy. Although they lived approxi-
mately three centuries apart, both men played a vital role in advancing carto-
graphic techniques that would pave the way for much more accurate and detailed
maps. Eratosthenes, using the principles of geometry, derived a highly accurate
measurement of theEarth’s size almost two centuries before the birth of Christ
and over a millennium before the planet was circumnavigated. He is also credited
with constructing the first grid system for cartographic representation, a major
achievement in that it established a means for accurately determining both dis-
tance and direction from a map. Ptolemy modified the grid system of Eratosthenes
and offered his own calculation of the earth’s circumference, although ironically,
his estimation contained a much greater error than that of his predecessor. His
coordinate system, however, provided the basis for the modern application of48 Cartography
Eratosthenes
Eratosthenes was a Greek geographer who may have been the first scholar to accurately cal-
culate the circumference of the earth. Remarkably, he was able to estimate the size of the
planet to within one percent of its actual circumference at the equator, depending on the
exact units of distance he may have used. His method was ingenious—by measuring the differ-
ence in the angle of elevation of the sun at solar noon between two locations on the summer
solstice, and assuming that both lay along the same longitude, he was able to deduce that the
distance between the two locations must be equal to one fiftieth of the earth’s circumference.
He also derived a system of latitude and longitude, which was later perfected by Ptolemy and
used in the West by mariners and geographers for centuries, and he may have calculated the
distance between the earth and the sun with reasonable accuracy. Eratosthenes also was
skilled in the science ofcartographyand composed one of the first maps of the world in
antiquity, based on the limited geographical knowledge at his disposal. Eratosthenes served
as the head librarian for some time at the Library of Alexandria, one of the ancient world’s
most important scholarly collections.