Tuesday, October 14, 2008

Peirce's Quincuncial

As you may know, C. S. Peirce worked for the USGS. One of the things he did while there was design a map projection that has come to be known as Peirce's quincuncial. In it one hemisphere is presented as a square, and the other hemisphere as four isosceles triangles around the sides, creating a map that is genuinely square and tiles nicely.

* Wikipedia has a good account of the basics

* Peirce's paper on it is available at Google Books. (Notice that he uses the tessellation property in the picture here.)

* Sean Carroll discussed it at Cosmic Variance a few years ago, as did John Baez.

* The same principles of projection can be used to make interesting pictures.

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