**Long Island Sound Triangulation 1881** This 1881 U.S. Coast Survey triangulation chart documents the precise geodetic measurements across Long Island Sound, spanning the waters between New York, Connecticut, and New Jersey. The intricate network of triangulation lines reveals the mathematical precision required to map this complex coastal waterway during the height of 19th-century American maritime commerce. Printed with exceptional clarity on heavy paper stock, preserving the fine detail of the survey annotations and coastal features.