County of Cornwall, England, 1748 (Image 6 of 7) (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: A new and accurate map of the county of Cornwall : from an actual survey, made by Thos. Martyn. It was printed and sold by Robt. Sayer, map & print seller opposite Fetter Lane Fleet Street in 1748. Scale [ca. 1:65,000]. This layer is image 6 of 7 total images of the nine sheet source map, representing the southwest portion of the map.The image inside the map neatline is georeferenced to the surface of the earth and fit to the 'British National Grid' coordinate system. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features such as drainage, cities and other human settlements, roads, administrative boundaries, shoreline features, and more. Relief shown pictorially. Includes inset of the Isles of Scilly and illus. of "The arms of the nobility and gentry that have subscrib'd for this map."This layer is part of a selection of digitally scanned and georeferenced historic maps from the Harvard Map Collection. These maps typically portray both natural and manmade features. The selection represents a range of originators, ground condition dates, scales, and map purposes.

Historic paper maps can provide an excellent view of the changes that have occurred in the cultural and physical landscape. The wide range of information provided on these maps make them useful in the study of historic geography, and urban and rural land use change. As this map has been georeferenced, it can be used in a GIS as a source or background layer in conjunction with other GIS data.

source map publication date.

map.

None.

The georeferenced raster is a faithfully reproduced digital image of the original source map. Some differences may be detected between the source graphic used and the raster image due to the RGB values assigned that particular color. The intent is to recreate those colors as near as possible. Data completeness for raster digital image files reflect content of the source graphic. Features may have been eliminated or generalized on the source graphic due to scale and legibility constraints The horizontal positional accuracy of a raster image is approximately the same as the accuracy of the published source map. The lack of a greater accuracy is largely the result of the inaccuracies with the original measurements and possible distortions in the original paper map document. There may also be errors introduced during the digitizing and georeferencing process. In most cases, however, errors in the raster image are small compared with sources of error in the original map graphic. The RMS error for this map is 198.45487 meters. This value describes how consistent the transformation is between the different control points (links). The RMS error is only an assessment of the accuracy of the transformation.

ESRI ArcGIS 9.3.1.

Not applicable.