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.
^Erasmus Bartholin
School of Mathematics and Statistics. University of St Andrews, Scotland
^Erasmus Bartholin, Experimenta crystalli islandici disdiaclastici quibus mira & insolita refractio detegitur (Copenhagen ("Hafniæ"), Denmark: Daniel Paulli, 1669). English translation: Experiments with the double refracting Iceland crystal which led to the discovery of a marvelous and strange refraction, tr. by Werner Brandt. Westtown, Pa., 1959.
