Depths shown by soundings and shading. "Apr. 7, 1786." Colored in outline. Available also as a digital image through the Harvard University Web site. Electronic reproduction. Cambridge, Mass. : Harvard Geospatial Library, 2006. Georeferenced image for use in a GIS.
Depths shown by soundings and shading. "Apr. 7, 1786." Colored in outline. Available also as a digital image through the Harvard University Web site. Electronic reproduction. Cambridge, Mass. : Harvard Geospatial Library, 2006. Georeferenced image for use in a GIS.