Clavus, Claudius (or Nicholas Niger), the latinized form of the name of the old Danish cartographer Claudius Claussön Swart, b. in the village of Salling, on the Island of Fünen, 14 September, 1388; date of death unknown. He was the first man to make a map of North-Western Europe, which, moreover, included the first map of Greenland. He was apparently an ecclesiastic. In the course of his frequent journeys he went to Italy, where in 1424 he aroused much interest among the Humanists of Rome by announcing that in the Cistercian monastery of Soröe, near Roeskilde, he had seen three large volumes which contained the "Ten Decades" of Livy; according to his own statement he had read the titles of the chapters (decem Livii decades, quarum capita ipse legisset). Through his intercourse with the Humanists he became acquainted with the maps and descriptions of Ptolemy, and was thus led to supplement the work of Ptolemy by adding to it a chart and description of the North-West country. Clavus first turned his knowledge of Scandinavia and Greenland to account in the geographical drawing and description which has been preserved in the Ptolemy MS. of 1427 of Cardinal Filiaster. The manuscript is now in the public library of Nancy. Descriptions of it have been repeatedly given by Waitz, Nordenskjöld, Storm, and others. The facsimile of Clavus's map and his description of the parts contained, which were published by Nordenskiöld and Storm, show that he gave Greenland and Iceland the correct geographical position, namely, west of the Scandinavian Peninsula.

Far more important, however, for the history of cartography is the second map and description of North-Western Europe and Greenland that Clavus produced. As yet, unfortunately, the original of this work has not been found, nor does any copy contain both the map and the description. This second map has been preserved in the works of the German cartographers, Donnus Nicholas Germanus and Henricus Martellus Germanus, who lived at Florence in the second half of the fifteenth century. Until recently, the descriptive text belonging to the map has only been known by the citations of Schöner and Friedlieb (Irenicus); the complete text was not known until it was found by Björnbo in two codices in the imperial library at Vienna. Björnbo's discovery is especially important as it is now certain that Claudius Clavus was actually in Greenland and that he claims to have pushed his journey along the west coast as far as 70° 10' N. lat. Another fact that lends importance to this discovery is that an explanation has at last been found for the incomprehensible names on the old maps of Greenland. Local names in Greenland and Iceland, so entirely different from those that appear in the Icelandic sagas, for a long time served the defenders of the Zeni as an argument that the map of Greenland was the work of the elder Zeno. It is now clear from the list of names given by Clavus that the Icelandic names on the map are not the real designations of the places, but merely the names of Runic characters. In the same manner, when he came to Greenland, Claudius Clavus used the successive words of the first stanza of an old Danish folk-song, the scene of which is laid in Greenland, to designate the headlands and rivers that seemed to him most worthy of note as he sailed from the north-east coast of Greenland around the southern end, and up the west coast. In the linguistic form of the words the dialect of the Island of Fünen is still evident. The discovery also makes clear how the younger Zeno was able to add to the forged story of a journey made in 1558 a comparatively correct map of the northern countries, and how he came to make use of the lines beginning:— Thaer boer eeynh manh ij eyn Groenenlandz aa" etc., which run in English:—

The second map of Clavus exercised a great influence on the development of cartography. As Clavus in drawing his map of North-Western Europe and Greenland made use of all the authorities to be had in his time, e.g. Ptolemy's portolanos (marine maps) and itineraries, so the map-makers of succeeding centuries adopted his map, either directly or indirectly: thus, in the fifteenth century, Donnus Nicholas Germanus and Henricus Martellus; in the sixteenth century, Waldseemüller, Nicolò Zeno, Ruscelli, Moletius, Ramusio, Mercator, Ortelius; in the seventeenth century, Hondius, Blaeu, and others; in the eighteenth century, Homann and his successors. It is evident that scarcely any other map has exerted so permanent an influence as the map of Greenland by Claudius Clavus, "the first cartographer of America".

Storm, Den danske Geograf Claudius Clavus eller Nicolaus Niger (Stockholm, 1891); Björnbo and Petersen, Fyenboen Claudius Claussön Swart (Copenhagen, 1904); Fischer, Die kartographische Darstellung der Entdeckungen der Normannen in Amerika in Proceedings of the Internat. Amer. Congress of 1904 (Stuttgart, 1906).

Joseph Fischer.