Wendelin (Vendelinus), Gottfried
WENDELIN (VENDELINUS), GOTTFRIED
(b. Herck-la-Ville (or Herk), Belgium, 6 June 1580; d. Ghent, Belgium, 1667), astronomy, meteorology, natural science, humanism, law.
In the laudatory style of the period, Wendelin was called the Ptolemy of his age. He studied first in his native place and then at Tournai and at Louvain, where at the age of seventeen he observed a lunar eclipse. He subsequently spent time in Nuremberg, Marseilles, Rome, and Digne, before returning to Liége and Herck. He was ordained priest at Brussels and became a curate and a canon of Condé and Tournai, where he was an official of the cathedral. Like many deeply Catholic scientists, he was more attracted by the physical sciences and mathematics than by the biological sciences.
A convinced Copernican, Wendelin upheld his views with a courage that is the more impressive when it is recalled that both Descartes and Galileo were obliged to have their works (respectively, Discours de la méthode  and Discorsi ) printed in Protestant Holland. The Protestant presses of Leiden had become vital organs in the dissemination of new ideas. Wendelin’s audacity appears all the greater in the light of the misfortunes experienced even much later, in 1691. by Martin-Étienne van Velden, a professor at the University of Louvain. A century and a half after Copernicus (1543) and four years after Newton (1687), the rector of the university formally ordered the arrest of van Velden for having attempted to make a student say that one cannot doubt the Copernican system regarding the movement of the planets around the sun.1
Wendelin was apparently the first to propose a law of the variation of the obliquity of the ecliptic. According to Bigourdan, Wendelin also observed the influence of temperature on the period of the oscillations of a pendulum, noting that the oscillations are more numerous in winter than in summer. He also recognized—as Galileo had not—that an increase in amplitude increases the period of the oscillations.
Wendelin corresponded with Mersenne, Gassendi, whom he taught astronomy, and Constantijn Huygens.2 They were all younger than Wendelin. In a letter to Plempius, Descartes solicited Wendelin’s opinion of his Géométrie.3 In a letter to Colvius, Descartes wrote: “I’auois aussi desia vu la lampe de Vendelinus [G. W. Luminarcani …Lampas]; mais elle ne m’s point esclairé.”4 Finally, in a letter to Constantijn Huygens, Descartes praised Wendelin for his Pluria purpurea, calling him “homme scauant aux Mathematiques, et de tres-bon esprit.”5
While Wendelin does not appear in the first four volumes of The Correspondence of Isaac Newton, he does figure among the seventy-one authors cited in the Principia (1687). There he has the honor of being mentioned in the company of Ptolemy, Huygens, Copernicus, Street, Tycho Brahe, and Kepler (book III, proposition 4, theorem 4).
1. See J. Pelseneer, in Biographie nationale publiée par l’Académie royale de Belgique, XXVI (1936-1938), cols. 562–567.
3. See letter of 3 October 1637, in Oeuvres de Descartes, C. Adam and P. Tannery, eds., I (Paris, 1897), 411.
4. Letter of 5 September 1643, in Oeuvres de Descartes, Supplément, Index général (1913), 16.
5. Letter of 5 October 1646, in Oeuvres de Descartes, IV, 516.
I. Original Works. Wendelin’s works are Loxias seu de obliquitate solis diatriba…(Antwerp, 1626); De diluvio liber primus (Antwerp, 1629); ld…secundus (incomplete); Aries seu aurei velleris encomium (ca. 1632); De tetracty Pythagorae dissertatio epistolica (1637); G. W. Luminarcani…Lampas (Brussels, 1644); Eclipses lunares ab anno 1573 ad 1643 observatae (Antwerp, 1644); Pluvia purpurea Bruxellensis (Paris, 1647); Leges salicae illustratae (Antwerp, 1649); Luminarcani, Teratologia cometica …(1652); De causis naturalibus, pluviae purpureae Bruxellensis …(London, 1655); Epistola didactica de calcedonio lapide …(ca. 1655); and Arcanorum caelestium Sphinx et Oedipus…(Tournai, 1658).
II. Secondary Literature. On Wendelin and his work, see the notice by Lucien Godeaux, in Biographie nationale publiée par l’Académie royale de Belgique, XXVII (1938), Cols. 180–184, with a bibliography.