Nicolaus Reimers

Nicolaus Reimers Baer (2 February 1551 – 16 October 1600), also Reimarus Ursus, Nicolaus Reimers Bär or Nicolaus Reymers Baer, was an astronomer and imperial mathematician to Emperor Rudolf II. Due to his family's background, he was also known as Bär, Latinized to Ursus ("bear").

Reimers was born in Hennstedt and received hardly any education in his youth, herding pigs until the age of 18. Yet, Heinrich Rantzau discovered his talents and employed him from 1574 to 1584 as geometer. Accordingly, Reimers in 1580 published a Latin Grammar and in 1583 his Geodaesia Ranzoviana. Rantzau also arranged a meeting with Tycho Brahe.

From 1585 to 1586 he was employed as a private tutor in Pomerania and from 1586 to 1587, Reimers stayed at the court of William IV, Landgrave of Hesse-Kassel in Kassel, where he met Swiss instrument maker Jost Bürgi (1552–1632). Both were autodidacts and thus had a similar background. As Bürgi did not understand Latin, Reimers translated Copernicus' De Revolutionibus Orbium Coelestium into German for Bürgi. A copy of the translation survived in Graz, it is thus called "Grazer Handschrift".

Reimers was a bitter rival of Tycho Brahe (his successor as imperial mathematician) after he tried to claim the Tychonic system as his own. Tycho complained that Ursus had plagiarized both his system of the world, as well as the publication of the mathematical model of prosthaphaeresis. History has sided with Ursus on the later issue, and he had stated that the technique was the invention of Paul Wittich and Jost Bürgi.

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