Vertical World

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Image: Prior Probability
Date and real source: I would love to know!

All maps involve choices: no single map can be "the" correct map, but all maps reveal something of the priorities of the cartographers who make them and the publishers who disseminate them. One of the most important choices -- especially for maps of the entire world -- is that of projection.

In representing a nearly spherical earth on a flat surface, mathematical bending, stretching, cutting and the like are needed, and the final result is a trade-off among four kinds of distortion. Perhaps one of these can be preserved, but certainly not all of them: 

size

shape

direction

distance

Which of these are favored depends upon the purpose of the map. I am not quite certain which have been preserved on this world map from China -- direction is definitely not, nor is size. The map draws attention to one of the cartographer's other important choices: the orientation of the map (we almost always use landscape rather than portrait) and the choice of a center.

The choice to center the map on the Indian Ocean has a number of interesting implications here. Students in my Advanced Global Thinking course will be asked to write about what some of these are.