Dicuil
Dicuilus(or the more vernacular version of the name Dícuil) was a monk and geographer, born during the second half of the 8th century. Noble and Evans identify him as aGaeland suggest that he had probably spent time in theHebrides.[1]
Background[edit]
The exact dates of Dicuil's birth and death are unknown. Of his life nothing is known except that he probably belonged to one of the numerous Irish monasteries of theFrankish Kingdom,and became acquainted by personal observation with islands nearEnglandandScotland.From 814 and 816 Dicuil taught in one of the schools ofLouis the Pious,where he wrote an astronomical work, and in 825 a geographical work.[2]
Dicuil's reading was wide; he quotes from, or refers to, thirty Greek and Latin writers, including the classicalHomer,Hecataeus,Herodotus,Thucydides,Virgil,PlinyandKing Juba,the late classicalSolinus,the patristicSt IsidoreandOrosius,and his contemporary the Irish poetSedulius.In particular, he professes to utilize the alleged surveys of the Roman world executed by order ofJulius Caesar,AugustusandTheodosius II.[3]
Based on similarities of style, it has been suggested that Dicuil may be the same person as the anonymousHiberno-Latinpoet and grammarian known asHibernicus exul.[4]
Astronomical computus[edit]
The astronomical work is a sort ofcomputusof five books, in prose and verse. Four books are preserved in a manuscript which belonged formerly to the monastery ofSaint-Amandin northern France, and is now atValenciennes.[5]A second manuscript is from the abbey of Saint Martin at Tours, and contains two chapters added to the fourth book, and two more chapters constituting a fifth book[6]
Book 1 contains material on calendars, on 19-year lunar cycles, and on versification. It also contains an account of the two methods of calculatingtriangular numbers:by summation of the natural numbers, or by the multiplication together of two consecutive numbers divided by two[7]
Book 2 contains material on the distance between the Earth and the heavens, and between the seven planets; methods for counting the lunar months; the monthly age of the moon; rules for calculating Easter and Lent;intercalary days(extra days) and subtracted days; solar and lunar years; more on versification.
Book 3 contains material on cycles of the stars; 19 year lunar cycles; other large cycles of the Sun and Moon; the first day of the natural year (the spring equinox in March).
Book 4 contains material on solar intercalary days and lunar subtracted days; and on the relative speed of travel of the Moon, Sun and stars.
De mensura Orbis terrae[edit]
Better known is theDe mensura Orbis terrae,a summary of geography, giving concise information about various lands. This work was based upon aMensuratio orbisprepared by order of EmperorTheodosius II(AD 435), a manuscript copy of which was possessed by theCarolingiancourt.Godescalchad already made use of this copy (781-783) for the composition of his celebratedEvangelistarium.Dicuil usesPliny the Elder,Gaius Julius Solinus,Paulus Orosius,Isidore of Seville,and other authors, and adds the results of his own investigations.[5]
In the nine sections he treats successively ofEurope,Asia,Africa,Egypt,andEthiopia,the area of the Earth's surface, the five great rivers, certain islands, the length and breadth of theTyrrhenian Sea,and the six (highest) mountains.[5]
Although mainly a compilation, this work is not without value. Dicuil is our only source for detailed information of the surveys performed by order of Theodosius II; his quotations, generally exact, are of service for the textual criticism of the authors mentioned; of great interest, too, are the few reports which he got from the travellers of his time; as, for instance, from the monk Fidelis who (possibly in 762 AD) journeyed alongthe canal then still existing,between the RiverNileand theRed Sea;and from clerics who had visited theFaroe Islandsand lived possibly inIcelandfor six months during the summer of 795. Among their claims are the perpetual day at midsummer in "Thule,"where there was then" no darkness to hinder one from doing what one would. "They also described navigating the sea north of Iceland on their first arrival, and found it ice-free for one day's sail.[3]
Editions[edit]
The geography manuscript was known to Marcus Welser,Isaac Vossius,Claudius Salmasius,Jean Hardouin,andJohann Daniel Schöpflin;it was first printed with the title:Dicuili Liber de mensura orbis terrae ex duobus codd. mss. bibliothecae imperialis nunc primum in lucem editus a Car. Athan. Walckenaer(Paris, 1807).
- J. J. Tierney,Dicuil: Liber de Mensura Orbis Terrae,(Dublin 1967).
Notes[edit]
- ^Noble, Gordon & Evans, Nicholas (2022),Picts:Scourge of Rome, Rulers of the North,Birlinn,Edinburgh, pp. 273 & 274,ISBN978-1-78027-778-3
- ^Esposito, Mario; Dicuil (1906). "An Unpublished Astronomical Treatise by the Irish Monk Dicuil".Proceedings of the Royal Irish Academy, Section C.26:378–446.
- ^abOne or more of the preceding sentences incorporates text from a publication now in thepublic domain:Beazley, Charles Raymond(1911). "Dicuil".InChisholm, Hugh(ed.).Encyclopædia Britannica.Vol. 8 (11th ed.). Cambridge University Press. p. 200.
- ^Esposito, Mario(1990).Lapidge, Michael(ed.).Irish Books and Learning in Mediaeval Europe.Aldershot: Variorum. p. 461.ISBN0860782611.Retrieved27 October2017.
- ^abcHartig, Otto. "Dicuil." The Catholic Encyclopedia. Vol. 4. New York: Robert Appleton Company, 1908. 18 Feb. 2015
- ^Cordoliani, A. "Le comput de Dicuil", Cahiers de civilisation médiéval, 3/11, 1960, 325-337
- ^Ross, H.E. & Knott, B.I. "Dicuil (9th century) on triangular and square numbers." British Journal for the History of Mathematics, 2019,34 (2), 79-94.https://doi.org/10.1080/26375451.2019.1598687.
References[edit]
- Herbermann, Charles, ed. (1913)..Catholic Encyclopedia.New York: Robert Appleton Company.
| International | |
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| National | |
| Academics | |
| People | |
| Other | |
- 8th-century births
- 9th-century Irish poets
- 8th-century Irish writers
- 9th-century writers in Latin
- 9th-century Christian monks
- 9th-century astronomers
- Irish Christian monks
- Irish explorers
- Irish astronomers
- Irish expatriates in France
- Irish male poets
- Irish writers in Latin
- Carolingian poets
- Irish scholars and academics
- Medieval Gaels
- Thule