Position on earth:

N40 43.939 W073 59.108 as per Google Earth. Thanks to Holspie on the GroundSpeak Forums.

# Horizontal Control

This marker represents a specific point on the globe. A specific point on the globe, in the northern hemisphere, in the United States of America, in New York City, on 14th Street.

A geodetic control point is a monumented or otherwise marked, survey point, established for the purpose of providing geodetic reference for mapping and charting activities and for a wide variety of engineering and scientific applications. It is used to establish property lines, or alignment for various infrastructure components such as sewers or curb lines.

*from NGS Surveyor on the Groundspeak Forums*:

A Triangulation Station is a survey point established during a survey utilizing the triangulation surveying method. Triangulation consists of observing the angles at the vertices of adjacent triangles, measuring the lengths of some sides, and computing the lengths of the remaining sides. The goal of this procedure is to determine the horizontal positions (latitude and longitude) of the vertices of each triangle (the points marked by TRIANGULATION STATION disks). The triangulation method thus produces accurate horizontal positions but only approximate elevations. Later, if a leveling survey crew was nearby, they may have leveled to one or more of the disks providing more accurate elevations.