This is the FIRST PUBLISHED MAP OF THE ORDNANCE SURVEY, a monumental moment and achievement in British cartography. Despite being published for the Ordnance it was never incorporated into the National Series. The second map to be published and the first of the National Series was that of Essex. Interestingly the Kent was not included until 1816-19 but would still be numbered 1-4. Although the imprint is dated 1 January 1801 its publication appears to have been slightly later according to the advertisement in ‘The Times’ on 13 January. The first triangle of what is now the national grid was observed by Captain Mudge from the tower of Lympne Castle to Dungeness Lighthouse. From here the survey spread out over the whole of Great Britain. Its accuracy is a testament to the work, recent satellite mapping was compared by the Ordnance Survey with Mudge’s map which was found to be only a few inches out. The main roads are coloured in brown as usual and the detail is remarkable. A nineteenth century owner has accurately applied the principal railways of the county an analysis of which indicates them upto about 1862. The whole was engraved by Thomas Foot. The Ordnance Survey evolved in 1824 into the format that we are familiar with which ignores county borders. Up to that date the traditional county format was maintained. A nice example with the Board of Ordnance gilt stamp on the cover. Provenance: with the ownership inscription of W. Terrill of Ashford. Burgess (2009) no. 81; Hellyer, Roger (1999) ‘Ordnance Survey small-scale maps’ no. 1.1; Rodger (1972) no. 235.