This Colgu, or Colgan, himself wrote a book in Irish, called "The Besom of Devotion," which appears to be now lost. A litany of his still remains. The great eleventh-century annalist, Tighearnach, was an alumnus of Clonmacnois. So, too, was the reputed author of the "Chronicon Scotorum," O'Malone, in 1123. The Annals of Clonmacnois was one of the books in the hands of the "Four Masters," but it is now lost, and a different book called by the same name (the original of which has also perished) was translated into English by Macgeoghegan in 1627.[18] The celebrated Leabhar na h-Uidhre [Lowar na Heera] or "Book of the Dun Cow," compiled about the year 1100, emanated from this centre of learning. Like Clonfert, and every other home of Irish civilisation, the city of Clonmacnois fell a prey to the barbarians. The Northmen plundered it or burnt it, or both, on ten separate occasions. Turgesius, their leader, set up his wife Ota as a kind of priestess to deliver oracles from its high altar;[19] and some of the Irish themselves, reduced to a state of barbarism by the horrors of the period, laid their sacrilegious hands upon its holy places; and afterwards the English of Athlone stepped in and completed its destruction. It now remains only a ruin and a name. Another very celebrated school was that of Bangor, on Belfast Loch, founded by Comgall, the friend of Columcille, between 550 and 560. It soon became crowded with scholars, and next to Armagh it was certainly the greatest school of the northern province, and produced men of the highest eminence at home and abroad. Its fame reached far across the sea. St. Bernard called it "a noble institution, which was inhabited by many thousands of monks;" and Joceline of Furness, in the twelfth century, called it "a fruitful vine breathing the odour of salvation, whose offshoots extended not only over all Ireland, but far beyond the seas into foreign countries, and filled many lands with its abounding fruitfulness." The most distinguished of Bangor's sons of learning were Columbanus, the evangeliser of portions of Burgundy and Lombardy; St. Gall, the evangeliser of Switzerland; Dungal, the astronomer; and later on, in the twelfth century, Malachy O'Morgair, who, though not known as an author, distinguished himself in the province of Church discipline.