“ He visited Frauenburg, where Copernicus had made his observations, took a master’s degree at Rostock, and at Copenhagen found a patron in Christian Friis, chancellor of Denmark, who gave him employment in his household. Appointed in 1603 rector of the school of Viborg, he was elected two years later to a professorship in the university of Copenhagen, and his promotion to the chair of mathematics ensued in 1607. ”

“ LONGOMONTANUS (or Longberg) , CHRISTIAN SEVERIN (1562–1647) , Danish astronomer, was born at the village of Longberg in Jutland, Denmark, on the 4th of October 1562. The appellation Longomontanus was a Latinized form of the name of his birthplace. His father, a poor labourer called Sören, or Severin, died when he was eight years old. ”

“ Pentas Problematum Philosophiae (1623) ; De Chronolabio Historico, seu de Tempore Disputationes tres (1627) ; Geometriae quaesita XIII. de Cyclometria rationali et vera (1631) ; Inventio Quadraturae Circuli (1634) ”