Legend for the 1817 Whiteside map, showing the symbol used to indicate a grist mill.

Source: Pennsylvania, "Melish-Whiteside Maps, 1816-1821, Record Group 17," digital images, Pennsylvania State Archives, Land Records (http://www.phmc.state.pa.us/bah/dam/rg/di/r17-534WhitesideMaps/r017-534WhitesideMapInterface.htm : downloaded 2 December 2010), Legend of map symbols; Pennsylvania Historical and Museum Commission, Bureau of Archives and History.