explains the treaty mentioned in the Heimskringla, giving to Norway all lands lying west of Scotland between which and the mainland a vessel could pass with her rudder shipped.... This was not one of the very largest ships, for some of them had thirty oars on each side, and vessels carrying from twenty to twenty-five were not uncommon. The largest of these were called Dragons, and other sizes were known as Serpents or Cranes. The ship itself was often so built as to represent the name it bore: the dragon, for instance, was a long low vessel, with the gilded head of a dragon at the bow, and the gilded tail at the stern; the moving oars at the side might represent the legs of the imaginary creature, the row of shining red and white shields that were hung over the gunwale looked like the monster's scales, and the sails striped with red and blue might suggest his wings. The ship preserved at Christiania is described as having had but a single mast, set into a block of wood so large that it is said no such block could now be cut in Norway. Probably the sail was much like those still carried by large open boats in that country,--a single square on a mast forty feet long.[194] These masts have no standing rigging, and are taken down when not in use; and this was probably the practice of the Vikings." [Footnote 194: Perhaps it may have been a square-headed lug, like those of the Deal galley-punts; see Leslie's _Old Sea Wings, Ways, and Words, in the Days of Oak and Hemp_, London, 1890, p. 21.] [Sidenote: The climate of Greenland.]