A Brill Calendar: October 30

Snellius and his Law of Refraction

Few scientists during the first half-century of Leyden University illustrate and exemplify the intellectual, educational and scholarly climate better than Willebrord Snel van Royen.

Born in the city in 1580, when the University celebrated its first ‘lustrum’, and son of a founding professor, he succeeded his father and occupied his Chair in 1613; until the day he died in his home-town October 30, 1626. In the science of optics he is chiefly remembered for a ground-breaking analysis of the refraction of a ray of light crossing surfaces between two different substances, resulting in the physical law he discovered in 1621. Since he didn’t publish it, his rightful place in the chronicles of theoretical science had to wait a while, until the days of Christiaan Huygens and René Descartes. The dictum ‘publish or perish’ didn’t yet apply in those days as mercilessly as it did later.

During this earlier time, it is seldom seen that Professors shoulder scientific tasks also outside of lecture-halls, libraries, and reading-rooms. Yet ‘Snellius’ – as he Latinized his surname – took it on himself to study the shape of the globe better than had been done before, in order to determine on it exact positions and measure precise distances: essential activities for an era in which maps and map-making contributed greatly to the mercantile prosperity in Dutch cities.

His University had no reason to look with envy at the scholastic glories (and dissipations) of Oxford and Cambridge and of the Sorbonne and Salamanca. Snellius’ ‘Alma Mater’ could only be compared realistically to those of Heidelberg and Geneva, where a new mental climate reigned and new protocols were developing to spread and publish new results. Snellius tried, for instance, to determine the length of meridians by measuring, more painstakingly than ever had been done, the distance between Alkmaar to Bergen op Zoom, encompassing in its North-South direction the whole embryonic Republic.