Detail from an engraving based on one of Robert Erskine’s military maps, showing the Croton Area in 1778-1780. The full map is below.
Since this was produced for military purposes it notes the location of Cortlandt Furnace (as well as the Sing Sing silver mine).
This copy was printed and folded into Washington Irving’s multi-volume Life of George Washington, published in 1859.
CROTON 