When Pytheas returned to his ship in some haven of Cantion he proceeded northwards. His next observation gave 17 hours as the length of the longest day. This would be in latitude 54° 2′ N., somewhere in the neighbourhood of Flamborough Head. Still coasting to the north in his great voyage of discovery, Pytheas came to a point at the northern end of Britain which, by a similar method of finding the latitude, must have been Tarbat Ness in Ross-shire. As he advanced towards the Arctic Circle he found that the cultivated grains and fruits and almost all the domesticated animals gradually disappeared. The people in the far north were reduced to living mainly on herbs and roots. The intrepid explorer still pressed onwards to discover the northernmost point of the British Isles. Coasting along the shores of Caithness and the Orkney Islands he finally arrived, conjecturally, at Unst Island, the northernmost of the Shetland Isles. Pytheas gives the name of Orcas to this extreme point of the British Isles, a name which in later times was transferred to the Orkneys or Orcades. It was at Orcas that Pytheas received information of an Arctic land called _Thule_[9], at a distance of six days’ sail, and near the frozen ocean. There was no night there in the summer solstice. During one season the night was continuous, and during another it was continual day. Pytheas does not say that _Thule_ was an island, nor that he had been there. It was possibly the coast of Norway in the neighbourhood of Alstenoe and the Vefsen-fjord. Pytheas also received reports of the physical aspect of the Arctic region beyond Thule. His account has been turned into nonsense by Strabo, copying from the explorer’s adverse critic Polybius. Yet even as we have it, the real meaning is clear enough. It is a good description of a fog at the edge of broken-up pack ice and sludge, “which can neither be travelled over nor sailed through.” Pytheas was thus not only the discoverer of Britain, but the first explorer who received information respecting the Arctic regions. He was, as Professor Rhys has truly said, “one of the most intrepid explorers the world has seen.” To have taken five observations of the lengths of the longest days the voyage must have occupied about six years. Sailing south from Orcas, Pytheas returned to Cantion, and eventually to his home at Massilia, whence he is said to have set out on another expedition to examine the mouth of the Elbe, and the sources of amber. He lived to return once more to his home. Pytheas wrote one, if not two books to describe the events and results of his memorable voyages. Both are unfortunately lost. We only know the story from the extracts in Strabo and other later writers[10].