LONGOMONTANUS (or LONGBERG),

See also:

• CHRISTIAN
• CHRISTIAN, WILLIAM (1608-1663)

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 Soren, or Severin, died when he was eight years old . An uncle thereupon took charge of him, and procured him instruction at Lemvig; but after three years sent him back to his mother, who needed his help in field-work . She agreed, however, to permit him to study during the winter months with the clergy-man of the parish; and this arrangement subsisted until 1577, when the illwill of some of his relatives and his own desire for knowledge impelled him to run away to Viborg . There he attended the grammar-school, defraying his expenses by manual labour, and carried with him to Copenhagen in 1588 a high reputation for learning and ability . Engaged by Tycho Brahe in 1589 as his assistant in his great astronomical observatory of Uraniborg, he rendered him invaluable services there during eight years . He quitted the island of Hveen with his master, but obtained his discharge at Copenhagen on the 1st of June 1597, for the purpose of studying at some German universities . He rejoined Tycho at Prague in January 1600, and having completed the Tychonic lunar theory, turned homeward again in August . 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 . This post he held till his death, on the 8th of October 1647 .

Longomontanus, although an excellent astronomer, was not an advanced thinker . He adhered to Tycho's erroneous views about

refraction, held comets to be messengers of evil and imagined that he had squared the circle . He found that the circle whose diameter is 43 has for its circumference the square root of 18252—which gives 3.14185 . . . for the value of r . John Pell and others vainly endeavoured to convince him of his error . He inaugurated, at Copenhagen in 1632, the erection of a stately astronomical tower, but did not live to witness its completion . Christian IV. of Denmark, to whom he dedicated his Astronomia Danko, an exposition of the Tychonic system of the world, conferred upon him the canonry of Lunden in Schleswig . The following is a list of his more important works in mathematics and astronomy: Systematis Mathematici, &c . (1611) ; Cyclometria e Lunulis reciproce demonstrata, &c . (1612) ; Disputatio de Eclipsibus (1616) ; Astronomia Danica, &c . (1622) ; Disputationes quatuor Astrologicae (1622); 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); Disputatio de Matheseos Indole (1636); Coronis Problematica ex Mysteriis trium Numerorum (1637); Problemata duo Goemetriaa (1638); Problema contra Paulum Guldinum de Circuli Mensura (1638) ; Introductio in Theatrum Astronomicum (1639) ; Rotundi in Plano, &c . (1644) ; Admiranda Operatio trium Numerorum 6, 7, 8, &c .

(1645) ; Caput tertium Libri primi de absoluta Mensura Rotundi plani, &c . (1646) . See E . P . F . Vindingius, Regia Academia Havinensis, p . 212 (1665) ; R . Nyerup and Kraft, Almindeligt Litteraturlexikon, p . 350 (1820); Ch . G . Jocher, Allgemeines Gelehrten-lexikon, ii . 2518, iii .

2111; Jens

Worm, ForsOg til et Lexikon over danske, norske og islandske laerde Maend, p . 617, 1771, &c.; P . Bayle, Hist. and Grit . Dictionary, iii . 861 (2nd ed . 1736); J . B . J . Delambre, Hist. de l'astr. moderne, i . 262; J . S . Bailly, Hist. de l'astr. moderne, ii .

141; J . L . E . Dreyer, Tycho Brahe, pp . 126, 259, 288, 299; F . Hoeffer, Hist. de l'astronomie, p . 391; J . Madler, Geschichte der Himmelskunde, i . 195; J . F . Weidler, Hist . Astronomiae, p .

451 .