 Although the chart of Robert Jager, 1629, ("Shipwrecks of the Goodwin Sands", R & B Larne) may leave something to be desired in accuracy of the coastline, it seems to suggest that the South Sand Head was farther south than it was in the next century and that the Head was turning back upon itself in cyclic movement.Early in the eighteenth century the South Sand Head was still so far south that the chart of Charles Labelye, 1736, (Public Records Office) shows a number of bearings, one of which runs through the two lighthouses then in existence and unmistakably strikes the Head.Richard Larne ("Shipwrecks of the Goodwin Sands") estimates the increase/decrease at 4000 feet a century.