Archive for January, 2011

“MapAnalyst is software for the accuracy analysis of old maps. Its main purpose is to compute distortion grids and other types of visualizations that illustrate the geometrical accuracy and distortion of old maps.” “http://mapanalyst.cartography.ch/

“The software uses pairs of control points on an old map and on a new reference map. The control points are used to construct distortion grids, vectors of displacement, accuracy circles, and isolines of local scale and rotation.”

Map Analysis of Gleason’s 1906 and Walling’s 1852 Concord Maps produced the maps shown below.

Twelve  control points were selected including Annursnac Hill, Bateman’s Pond, Punkatasset Hill, Buttrick’s Hill, Thoreau’s Birthplace, Hawthorne Lane Bridge,   Emerson’s Home, Egg Rock, Damon’s Mill, White’s Pond, Fairhaven Bay, and Walden Pond Cove.

Gleason’s 1906 and Walling’s 1852 Concord Maps were compared to the OpenStreetMap which is a collaborative project to create a free editable map of the world.

The resulting maps suggest that the accuracy of Gleason’s 1906 and Walling’s 1852 Concord Maps are fairly uniform and contain no gross geometric distortion relative to current geography.

Not surprising since Walling was a surveyor and Gleason used Walling data.

Significant distortion is more likely over a larger area such as a state or nation  rather than a town.

Note however the distortion caused by incorrect location of the Hawthorne Lane Bridge on the Gleason 1906, Walling 1852, F. W. Beers  1875 and USGS 1894 Reconnaissance maps, below.

They all show the bridge south of its correct location as shown by Thoreau on his 1853 and 1860 surveys:

“Plan of John B. Moore’s Farm, Concord, Mass. Surveyed by Henry D. Thoreau Feb. 1853”

Manuscript (pen and black ink), with annotations in red ink made in November 1886 by Albert E. Wood; 39cm x 86.5cm

Reproduced here courtesy of, the American Antiquarian Society, Worcester, Mass




Gleason’s 1906 Concord Map

Walling’s 1852 Concord Map

OpenStreetMap 2011 Concord Map used for map analysis reference

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