The map I have created here might have been in the head of an extremely widely travelled Dane in 890 – someone like Othere or Wulfstan (see: The Voyage of Othere and Wulfstan ) the merchant adventurers who King Alfred employed. The record of their verbal reports indicates that they understood the points of the compass and were guided by the stars. It is also reasonable to suppose that they understood the relationship between the height of the Sun and their location north and south.
I suggest that the expertise of the Scandinavian navigators should not be underestimated; it is known that magnetite (lodestones) could have been found in the South Islands (Hebrides and Western Isles) and it is likely that they would have possessed something like a primitive direction finder as the Uunartoq disc (see: Sun Compass). And then we have the possibility that they used the polarized light detection of Calcite (Iceland Spar) in determining the direction of the sun in overcast or sea mist conditions. Serious scientific work has been undertaken on such material and an accuracy of greater than 6 degrees has been obtained in laboratory conditions.
Othere and Wulfstan reported their journey around the northern coast of Norway in such a way as to describe its shape: recording the land to lie either to their steering board side or the other. Whether they committed this information to memory or to a scratched image on their ship’s timbers is irrelevant; they were, in fact, creating and visualising, a map, at least in their imagination..
It is inconceivable that, before calf skin and ink, human beings would not draw a diagram in the sand or on a wall with charcoal if it became necessary to describe a route of travel, or the shape of a ship, or the shape of a roof. The fact that these sketches were ephemeral communications was no problem for them, but has seemed to be an enormous problem for historians – who only acknowledge the artistically drawn maps on vellum by monks with more on their agendas than geometric accuracy. For myself, as an engineer who has many times found it far easier to draw an impromptu sketch with whatever implements were at hand for the benefit of manual workmen, I can assure these experts that that is what happens among relatively inarticulate men – who often possess an extra-ordinary spatial and graphical capability. How else would the Scandinavians have built their ships?
Geometry is a practical subject. You need it to build and make things. And, if you are a sailor who must avoid the rocks ahead by balancing the angle of the sail, to the forward motion of the ship and the direction of the wind, you must possess an intuitive geometric capability. It is interesting that Bede and Alcuin produced highly competent arithmetic works but very little on geometry. But then they wouldn’t, would they … because they were not practical men. It is not, therefore, surprising that the manuscripts of the seventh to ninth centuries contain no serious, practical, maps or construction drawings, but that does not mean that they did not exist – they were most likely scratched into the mud.
So what does all this mean? Well … look at the Danelaw boundary on a modern map of England. For the most part it follows Watling Street. Indeed, in the 878 Treaty, Watling Street is specifically mentioned. The boundary is a near straight diagonal that neatly divides the land into two parts. Is this a mere coincidence, or was it the intentional result of a geometric awareness of the shape of the British Isles – acknowledged by both the West Saxons and the Danes?