Pytheas in Harpers Dictionary of Classical Antiquities (1898)

Of Massilia in Gaul, a celebrated Greek navigator, who sailed to the western and northern parts of Europe, and wrote a book containing the results of his discoveries. He probably lived in the time of Alexander the Great or shortly afterwards. He appears to have undertaken two voyages, one in which he visited Britain and Thulé, and of which he probably gave an account in his work on the Ocean; and a second, undertaken after his return from his first voyage, in which he coasted along the whole of Europe from Gadira (now Cadiz) to the Tanaïs (Don), and the description of which probably formed the subject of his Periplus. Pytheas made Thulé a six days' sail from Britain, and said that the day and the night were each six months long in Thulé; hence some modern writers have supposed that he must have reached Iceland, while others have maintained that he advanced as far as the Shetland Islands. But either supposition is very improbable, and neither is necessary; for reports of the great length of the day and night in the northern parts of Europe had already reached the Greeks before the time of Pytheas. There has been likewise much dispute as to what river we are to understand by the Tanaïs. The most probable conjecture is that, upon reaching the Elbe, Pytheas concluded that he had arrived at the Tanaïs, separating Europe from Asia. See Antichan, Les Grands Voyages de Découvertes des Anciens (Paris, 1891).