Printed map. Two visual scales [175 mm = 6 Geographical Miles approximately]. Includes 2 insets: "The bases and Triangles reduced to an Horizontal Plane." and "Plan of the city of Durham [84 mm = 20 Chains approximately]." This note appears on map: "The Scales of Latitude and Longitude round this Map are fixed agreeable to the following observations made at Durham. N. Latitude 54 degrees 46' 50" taken by Mr. Professor Hornsby in 1765. Longitude 01 degree 15' 00" West of London. The Longitude is deduced from an accurate observation made of the Solar Eclipse in 1766 & compared with those made at London Sherborn." Acquired as part of the Cholmondeley Collection.