A Blog by International Students at Leiden University

Willebrord Snellius, the real star of Leiden

I have talked about great historians and law experts in the previous blog posts; today let me introduce you to a great mathematician and astronomer: Willebrord Snellius van Royen. I first encountered this name in my first semester in Leiden, accompanying one of my flatmates to his office at the Snellius building of Leiden University. Willebrord_Snellius.jpg

The Snellius building hosts the Mathematical Institute, the Leiden Institute of Advanced Computer Science (LIACS) and the Leiden Centre of Data Science; it is thus named after the Leiden-born scientist, known as Snel in the English-speaking world. Snellius was born in 1580 and later in life succeeded as mathematics professor to his father, who also thaught at Leiden University.

In his life Snellius travelled around Europe setting foot in France, Bohemia and Germany. Abroad, he met renowned colleagues, including the Flemish mathematician Adriaan van Roomen, the Danish astronomer Tycho Brahe and the distinguished Kepler.

According to the sources available, Snellius was the first to carry out a large-scale experiment to calculate the circumference of the planet Earth, after the Greek Eratosthenes in ancient times. Although the calculations revealed to be inexact (the actual circumference is 40,07 km, while he estimated a circumference of 38,653 km), he proved to be a skilful scientist in his field.

He described the method of calculation in his book Heratosthenes BatavusDe terrae Ambitus vera quantitate. Despite his calculations lacked precision, the experiment remains an important contribution to the mathematical branch of trigonometry. Snellius used the modern method of triangulation first described by the Dutch cartographer and physician Gemma Frisius around fifty years earlier.


Quadrant of Snellius
Image: Museum Boerhaave, Leiden

The main instrument used was a quadrant, today displayed at the Museum Boerhaave in Leiden. To carry out the calculations, Snellius counted on the help of two students from Austria. The book also contains the Snellius–Pothenot problem and its solution, that was wrongly attributed to Laurence Pothenot, a French mathematician from the 18th century.

Besides the Snellius building, a Lunar crater and three ships of the Royal Netherlands Navy have been named after hm.


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This entry was posted on September 22, 2019 by in Bruno, Leiden, Student City and tagged , , , , , .

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