Essex County, Massachusetts, 1825 (Raster Image)

This layer is a georeferenced raster image of the historic paper map entitled: The county of Essex, made by John G. Hales ; engraved by J.V.N. Throop. It was published June 19th, 1825. Scale [ca. 1:90,000]. The image inside the map neatline is georeferenced to the surface of the earth and fit to the Massachusetts State Plane Coordinate System, Mainland Zone (in Feet) (Fipszone 2001). 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 shows features such as roads, drainage, public buildings, churches, industry locations (e.g. mills, factories, mines, etc.), individual dwellings, town and county boundaries and more. Relief is shown by hachures. This layer is part of a selection of digitally scanned and georeferenced historic maps of Massachusetts from the Harvard Map Collection. These maps typically portray both natural and manmade features. The selection represents a range of regions, originators, ground condition dates (1755-1922), scales, and purposes. The digitized selection includes maps of: the state, Massachusetts counties, town surveys, coastal features, real property, parks, cemeteries, railroads, roads, public works projects, etc.

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.

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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, but in most cases, these are small compared with sources of error in the original map graphic. One source of error could be associated with the fact that this image is referenced to the Massachusetts State Plane (Feet) coordinate system, which is inconsistent with the original projection of the paper map, and may lead to discrepancies in the horizontal accuracy of the raster image. The RMS error for this map is 1138.80777 feet. 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.

Microsoft Windows 2000 Version 5.0 (Build 2195) Service Pack 4; ESRI ArcCatalog 9.1.0.722.

Not applicable.