Rossdavidh's Reviews > Rhumb Lines and Map Wars: A Social History of the Mercator Projection

Rhumb Lines and Map Wars by Mark Monmonier
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No matter what topic in science, math, or technology one chooses to investigate, however arcane, one can be convinced a priori of two things:
1) there are bitter divisions of opinion among the experts
2) there's a good xkcd webcomic about it (in this case, https://xkcd.com/977/)

Map projection is no exception in regards #1, either. The most public part of this, is the Mercator (if you don't know anything about map projections, this is the one you know) vs. Gall-Peters debate. This book is written, not by a pro-Mercator advocate, but rather by an anti-Peters advocate.

To compress a very long and detailed (and entertaining!) book into a few paragraphs: every 2D map is going to sacrifice something of accuracy (either in area, shape, distance, or some other thing) in order to get a 3D surface down to 2D. Several centuries ago, a fellow named Mercator did it in a particular way, in order to make a good map for European nautical navigators, so that they could easily use "rhumb lines" (don't ask) to find their way. Mercator's projection did (and still does) perfectly well for this, but it has the probably-not-entirely-coincidental affect of making northern Europe look a lot bigger than it should, relative to places like South America and Africa.

During the last half of the 20th century, a fellow named Peters developed a different projection (which it turns out had already been invented by a fellow named Gall 50+ years earlier), which showed each country in its appropriate relative size. This made it useless for nautical navigators, but then, Peters wasn't advocating its use for navigators. He was claiming that the Mercator projection, which hung on the wall in probably more than half of the classrooms in the world, was not a suitable map for the purpose of education, and it should be replaced with his.

The author of this book, while agreeing with the first part (Mercator is for nautical navigation, not education), objected to the second, claiming that there were many other much better projections available. Moreover, the claims by the Peters camp that Mercator and everyone who used his map since then were basically racists for doing so, was obviously galling (pun intended), since Mercator had perfectly valid technical reasons for making his map look the way it did, and the Gall-Peters projection would have been a disastrous choice for him to use for the task he was concerned with.

There is also the question of how influential map projections are over our worldview anyway, if the Mercator projection has not given us all an outsized view of the importance of Greenland in world affairs.

In between the first and last parts of the book, which are concerned more with the polemics of the topic, there are many chapters discussing the history, math, and technology of mapmaking, especially as concerns how to squash a 3D oblate spheroid onto a 2D surface. There are a lot of interesting stories, and the author covers them in an engaging way. For example, it was intriguing that in the early 40's, various Americans speculated in print that the Mercator projection had caused them to be isolationist, and disregard the threats from the east which eventually manifested as Pearl Harbor. This seems to be the cartographic equivalent of the Sapir-Whorf hypothesis in linguistics (that what language we speak influences how and what we think); it gets re-invented every couple generations.

In general, though, the interesting stuff is not the polemics, its the various ways that humans have used, and continue to use, maps. I continue to find them intriguing, and not only for practical purposes. In fact, I'm starting to have ideas for a new kind of map projection system of my own...
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Reading Progress

Finished Reading
October 20, 2019 – Shelved
November 5, 2019 – Shelved as: blue
November 5, 2019 – Shelved as: to-read

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