JAN MAYEN, an arctic island between Greenland and the north of Norway, about 71° N. 8° W. It is 34 m. long and 9 in greatest breadth, and is divided into two parts by a narrow isthmus. The island is of volcanic formation and mountainous, the highest summit being Beerenberg in the north (8350 ft.). Volcanic eruptions have been observed. Glaciers are fully developed. Henry Hudson discovered the island in 1607 and called it Hudson's Tutches or Touches. Thereafter it was several times observed by navigators who successively claimed its discovery and renamed it. Thus, in 1611 or the following year whalers from Hull named it Trinity Island; in 1612 Jean Vrolicq, a French whaler, called it Île de Richelieu; and in 1614 Joris Carolus named one of its promontories Jan Meys Hoek after the captain of one of his ships. The present name of the island is derived from this, the claim of its discovery by a Dutch navigator, Jan Mayen, in 1611, being unsupportable. The island is not permanently inhabited, but has been frequently visited by explorers, sealers and whalers; and an Austrian station for scientific observations was maintained here for a year in 1882-1883. During this period a mean temperature of 27.8° F. was recorded. JANSEN, CORNELIUS (1585-1638), bishop of Ypres, and father of the religious revival known as Jansenism, was born of humble Catholic parentage at Accoy in the province of Utrecht on the 28th of October 1585. In 1602 he entered the university of Louvain, then in the throes of a violent conflict between the Jesuit, or scholastic, party and the followers of Michael Baius, who swore by St Augustine. Jansen ended by attaching himself strongly to the latter party, and presently made a momentous friendship with a like-minded fellow-student, Du Vergier de Hauranne, afterwards abbot of Saint Cyran. After taking his degree he went to Paris, partly to recruit his health by a change of scene, partly to study Greek. Eventually he joined Du Vergier at his country home near Bayonne, and spent some years teaching at the bishop's college. All his spare time was spent in studying the early Fathers with Du Vergier, and laying plans for a reformation of the Church. In 1616 he returned to Louvain, to take charge of the college of St Pulcheria, a hostel for Dutch students of theology. Pupils found him a somewhat choleric and exacting master and academic society a great recluse. However, he took an active part in the university's resistance to the Jesuits; for these had established a theological school of their own in Louvain, which was proving a formidable rival to the official faculty of divinity. In the hope of repressing their encroachments, Jansen was sent twice to Madrid, in 1624 and 1626; the second time he narrowly escaped the Inquisition. He warmly supported the Catholic missionary bishop of Holland, Rovenius, in his contests with the Jesuits, who were trying to evangelize that country without regard to the bishop's wishes. He also crossed swords