Rasmus Bartholin

Bartholin was born in Roskilde. He was the son of Caspar Bartholin the Elder (1585–1629) and Anna Fincke, daughter of the mathematician Thomas Fincke.[1]

As part of his studies, he travelled in Europe for ten years. He stayed in the Netherlands, England, France and Italy. In 1647, he took a Master's degree at the University of Copenhagen. In 1654, he received a Doctoral degree at the University of Padua.

He was a professor at the University of Copenhagen, first in Geometry, later in Medicine. He was also dean of the faculty of medicine, librarian, and rector.[2] He wrote, in Latin, the first grammar of the Danish language, the 1657 De studio lingvæ danicæ.

Rasmus Bartholin is remembered especially for his discovery (1669) of the double refraction of a light ray by Iceland spar (calcite).[3] He published an accurate description of the phenomenon, but since the physical nature of light was poorly understood at the time, he was unable to explain it.[4] It was only after Thomas Young proposed the wave theory of light, c. 1801 that an explanation became possible.

He was a younger brother of Thomas Bartholin (1616–1680).[5]

• "De figura nivis". In Thomas Bartolin, De nivis usu medico observationes variae. Accessit D. Erasmi Bartholini de figura nivis dissertatio, p. PA241, at Google Books. Copenhagen: P. Haubold, 1661
• O'Connor, John J.; Robertson, Edmund F., "Erasmus Bartholin", MacTutor History of Mathematics Archive, University of St Andrews
• Bartholin, Erasmus 1625-1698 worldcat.org