From the author's Atlantic Neptune.
This chart of the southern coasts of Massachusetts and Rhode Island is representative of the level of detail contained in the charts of The Atlantic Neptune. The surveys of this coastline began in 1774, and were performed by engineers working under the supervision of Samuel Holland. With the inclusion of numerous soundings, the chart is able to convey the depth of the sea at various places in a two-dimensional form. Modern nautical charts use the same placement of soundings along coastlines to inform navigators of underwater dangers. It was imperative for 18th century mariners to have such safety information, as navigation of intricate and unknown coasts could be perilous.