The datum is defined by the observed heights of mean sea level at the 26 tide gauges and by the set of elevations of all bench marks resulting from the adjustment. A total of 106,724 kilometers of leveling was involved, constituting 246 closed circuits and 25 circuits at sea level.
George Washingtonâs Mount Vernon is located roughly 15 miles south of Washington, D.C. and 8 miles south of Alexandria, Virginia on the banks of the Potomac River, at the southern end of the George Washington Memorial Parkway.
By road : Vernon is 75 km from Paris. Leave Paris by the Pont de Saint-Cloud and take the highway A13 (towards Rouen) for 55 km until you reach exit 14 (Bonni res) or exit 16 (Douains). The A13 is free until Mantes-la-Jolie. The charge is 1.80 euros to go further. After the exit follow Vernon or Giverny signs.