On the Trig

William WordworthThis tour presents the origin and early years of the Trigonometrical Survey of England and Wales, later known as the Ordnance Survey.

Born out of military expediency, the Survey's famous one-inch-to-the-mile maps became an enduring expression of national identity.

  • Between two fires


    For much of its history, England found itself sandwiched between hostile powers to the north and south - a situation illustrated by this map, drawn around 1490 by the German cartographer and book illuminator, Henricus Martellus, who worked in Florence.

  • Troubled borders


    In the north, the defence of England's Scottish border was a constant concern for Elizabeth I. This map of Northumbria comes from an atlas of English and Welsh counties belonging to the queen's chief minister, William Cecil, Lord Burghley.

  • The bottom line


    The first stage in meeting the French challenge was to lay out a baseline from which a network of triangles could be extended through Greenwich and on to the Kent coast, from where it would be linked across the Channel to the triangulation of northern France.