Chart of Rockland Harbor

Detail of the Penobscot Bay Maine nautical chart, 1/40,000 scale. Note how the chart not only shows depths and navigational features, but it shows much information on land, including buildings, topography, locations of stone walls, and even where there are and aren't trees. By 1876, the Rockland breakwater was protecting the great number of vessels coming and going in pursuit of the lime trade.