(also W. Snell van Roijen, latinized name Willebrordus Snellius van Royen). Born 1580 in Leiden; died there Oct. 30, 1626. Dutch astronomer and mathematician.
Snell became a professor at the University of Leiden in 1613. He discovered the law of refraction of light that now bears his name. Using the triangulation method he developed, Snell between 1615 and 1617 measured in Holland an arc of meridian 1°11’30” in length. He solved the recession problem for three points; sometimes referred to as Snell’s problem, it is also known as Pothenot’s problem. Snell was the author of works on plane and spherical trigonometry.