DICUIL (fl. 825), Irish monastic scholar, grammarian and geographer. He was the author of the De mensura orbis terrae, finished in 825, which contains the earliest clear notice of a European discovery of and settlement in Iceland and the most definite Western reference to the old freshwater canal between the Nile and the Red Sea, finally blocked up in 767. In 795 (February 1-August 1) Irish hermits had visited Iceland; on their return they reported the marvel of the perpetual day at midsummer in “Thule,” where there was then “no darkness to hinder one from doing what one would.” These eremites also navigated the sea north of Iceland on their first arrival, and found it ice-free for one day’s sail, after which they came to the ice-wall. Relics of this, and perhaps of other Irish religious settlements, were found by the permanent Scandinavian colonists of Iceland in the 9th century. Of the old Egyptian freshwater canal Dicuil learnt from one “brother Fidelis,” probably another Irish monk, who, on his way to Jerusalem, sailed along the “Nile” into the Red Sea—passing on his way the “Barns of Joseph” or Pyramids of Giza, which are well described. Dicuil’s knowledge of the islands north and west of Britain is evidently intimate; his references to Irish exploration and colonization, and to (more recent) Scandinavian devastation of the same, as far as the Faeroes, are noteworthy, like his notice of the elephant sent by Harun al-Rashid (in 801) to Charles the Great, the most curious item in a political and diplomatic intercourse of high importance. Dicuil’s reading was wide; he quotes from, or refers to, thirty Greek and Latin writers, including the classical Homer, Hecataeus, Herodotus, Thucydides, Virgil, Pliny and King Juba, the sub-classical Solinus, the patristic St Isidore and Orosius, and his contemporary the Irish poet Sedulius;—in particular, he professes to utilize the alleged surveys of the Roman world executed by order of Julius Caesar, Augustus and Theodosius (whether Theodosius the Great or Theodosius II. is uncertain). He probably did not know Greek; his references to Greek authors do not imply this. Though certainly Irish by birth, it has been conjectured (from his references to Sedulius and the caliph’s elephant) that he was in later life in an Irish monastery in the Frankish empire. Letronne inclines to identify him with Dicuil or Dichull, abbot of Pahlacht, born about 760.
There are seven chief MSS. of the De mensura (Dicuil’s tract on grammar is lost); of these the earliest and best are (1) Paris, National Library, Lat. 4806; (2) Dresden, Regius D. 182; both are of the 10th century. Three editions exist: (1) C. A. Walckenaer’s, Paris, 1807; (2) A. Letronne’s, Paris, 1814, best as to commentary; (3) G. Parthey’s, Berlin, 1870, best as to text. See also C. R. Beazley, Dawn of Modern Geography (London, 1897), i. 317-327, 522-523, 529; T. Wright, Biographia Britannica literaria, Anglo-Saxon Period (London, 1842), pp. 372-376. (C. R. B.)