Sheet 42nw, Old Series 1". 181857. Brecknockshire, now part of Powys: Brecknock.
Sheet 42nw, Old Series 1". 181857. Brecknockshire, now part of Powys: Brecknock. Topography date omitted, geology revised to 1854, published 1857. Hand-coloured engraving, 38 x 54cm, cut, mounted on linen and folded to 19 x 13.5cm between marbled Stanford covers. Stencilled number in top right corner. Clean, colours bright. In good to very good condition.
About the England & Wales One Inch Old Series
The Geological Survey of England and Wales used the Old Series of the Ordnance Survey topographic map at a scale of one inch to the mile as its basemap, initially. These engraved basemaps were published and revised between 1805 and 1885; the sheet sizes varied and the layout and numbering system were eccentric. The Old Series geological maps were hand-coloured and without geological sections, which were published separately. The GS of E&W published the Old Series from 1850 to 1900, when it switched to the colour printing and the New Series one inch maps. However, old stock of the Old Series continued to be issued, hand-coloured, until the 1930s.