This layer is a georeferenced raster image of an historic paper map of Africa. This is a continental map of Africa originally created and published by Aaron and Samuel Arrowsmith in 1825. The features illustrated on this map includes: rivers, lakes, and coastal islands. 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, or other information associated with the principal map. This map was georeferenced by the Stanford University Geospatial Center using a Sinusoidal projection. This map is part of a selection of digitally scanned and georeferenced historic maps of Africa from the Oscar I. Norwich Collection at Stanford University. This historic paper map provides an historical perspective of the cultural and physical landscape during this time period. The wide range of information provided on these maps make them useful in the study of historic geography. As this map has been georeferenced, it also can be used as a background layer in conjunction with other GIS data. 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 937.096 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. This layer is presented in the WGS84 coordinate system for web display purposes. Downloadable data are provided in native coordinate system or projection.
