Robert Erskine (1735 – 1780) was a Scottish inventor and engineer who came to the British Thirteen Colonies in 1771 to run the ironworks at Ringwood, New Jersey, and later became sympathetic to the movement for independence. In 1776 during the American Revolutionary War, he designed an underwater cheval-de-frise installed across the Hudson River at the north end of Manhattan to prevent passage of British ships upriver. General George Washington appointed him as Geographer and Surveyor General of the Continental Army at the rank of colonel; Erskine drew more than 275 maps, mostly of the Northeast region.
$700,000
