Willebrord Snellius' Grave

There is a church in Leiden called Pieterskerk, or the Church of St. Peter. It’s a 900-year-old Gothic beauty, the oldest church in this small city half way between Amsterdam and The Hague. It’s also known as the Church of the Pilgrim Fathers, most famous to Americans as the Dutch refuge where the Mayflower separatists briefly hung out after leaving England, but before sailing to Massachusetts.

The church has been deconsecrated as a religious space since the early 1970s, so you can’t attend services there any more, Calvinist or otherwise. But you can visit the final resting place of one of the world’s great mathematicians, an All-Star named Willebrord Snellius.

Willebrord Snel van Royen is buried under the floor at Pieterskerk, his spot marked by a simple flat stone and small plaque. Snell, as he’s known to physics and astronomy students everywhere, is the brains behind the law of refraction, one of the fundamental laws of physics.

That alone would have secured his math chops, but his reach goes much further. Of his many milestones, he’s also credited with basically inventing triangulation as we know it, managing to figure out the circumference of the Earth to a remarkably accurate degree for the time.

In the Netherlands he is remember with particular fondness and pride for drafting the first accurate map of the country. He achieved it with his new brand of triangulation, climbing up a series of church towers to measure their distances with a giant quadrant. The map was so accurate—and therefor valuable to the Dutch military—that it was kept secret and unpublished until years later.

For all who aren’t familiar with Snell’s Law of refraction or may have forgotten it, there will be no pop quiz. Here you go: 

 Got it? Good.