Ptolemic World Map

Emerson and Freeman (1969) explain, “Columbus and his contemporaries based their theories concerning the shape of the earth and its position in the universe on the system of Ptolemy” (p. 1). Considering Ptolemy’s works was used by so many cartographers both in the West and the East, instead of assuming that Columbus used Plotemy’s world map, it is more logical to indicate that Columbus used a Plotemic world map (either a recreation of Plotemy’s original map or a map which was drawn in the Plotemic style).

Figure 7. A Ptolemic world map

As a result of using Ptolemy’s notes and maps as a source to understand the earth, Columbus assumed that he could find a short way to Asia by sailing through the Atlantic Ocean to the west; however he did not know that Ptolemy had miscalculations. Evelyn Sharp (1991) explains the three fundamental problematic issues with Ptolemy’s perception of the world which led Columbus to believe that there was a shorter way to Asia:
For one thing, it [Ptolemic map] shows the land mass of Europe and Asia stretching across 180 degrees from east to west, or halfway around the earth […] Secondly, on Ptolemy’s map the coast of Europe is plainly defined, but there is no coast line on the east. The edge of the map cuts right down through Asia, implying that the land kept going. How far? Nobody knew. The third point concerns the size of the earth […] His earth was only three-fourths its true size. (p. 21-22)

Using Ptolemy’s perception of the earth, Columbus had “a vision of a small earth with a long Asia wrapping around it leaving less water on the other side” (Evelyn, 1991, p. 22).This vision gave Columbus the idea that it was possible to sail west to Asia; but before he went on his first voyage to prove his theory, he needed more evidence.

A Story To Tell: Seeing Through the Minds of Two Admirals

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