William Smith (1769–1839) chose large scale topographic manuscript maps for recording his field observations. Those for the northeastern counties of Durham and Northumberland were at one inch to the mile. They were made by Andrew Armstrong, and published in 1768 and 1769, respectively. The copies acquired by Smith, and colored and annotated by him, are the only early large–scale manuscript maps to have survived. They offer a rare insight into how he carried out fieldwork in counties that were unfamiliar to him, as he began work on what would become his celebrated map of England and Wales with Part of Scotland, first published in 1815. The Durham map has a near complete delineation of the strata, but the Northumberland map has little more than an outline. The stratum Millstone Grit was added on both maps, and the ‘stratum’ Whinstone on the Northumberland map. These were omitted from Smith's 1815 map. On each map, Armstrong plotted lead mines and coal mines then operating. Smith made use of these, particularly on the Northumberland manuscript map. Armstrong gave names to several features on his Northumberland map, which hinted at some mining activity there. This did not escape Smith’s notice. In 1821 Smith, and his nephew John Phillips, began a fresh survey of northern England for the county maps that would form part VI of Smith’s New Geological Atlas. Some information was carried over from the early manuscript maps to later manuscript maps, for which the topographic county maps by John Cary were the base maps. This included some of the geological information that Armstrong had printed.