While the greater number of the most famous sea-lights have been erected upon the solid foundation offered by rock, in one or two instances notable works have been consummated upon sand. The two most remarkable achievements in this particular field of enterprise are the Rothersand lighthouse, off the coast of Germany, in the North Sea, and the Fourteen Foot Bank, in Delaware Bay, U.S.A. The Rothersand light became necessary owing to the expansion of the German mercantile marine and the development of the ports of the Weser and Elbe. The estuary of the Weser River is hemmed in by shoals and sandbanks, similar to those found at the entrance to Liverpool, London, and New York, rendering navigation extremely hazardous under the most favourable circumstances. Bremerhaven, on the Weser, had been selected as the home port for the North German Lloyd Atlantic liners, but it was threatened with abandonment unless the entrance to the waterway should undergo improvement. It was of no avail to dredge a deep channel through the treacherous ridges of sand, if the general proximity of the shoal were left unmarked. Consequently, in order to secure the interests of Bremerhaven, it was decided by the three border States--Prussia, Oldenburg, and Bremen--to provide a powerful light at this danger-point. The financial problem was solved by the agreement to levy a special tax upon all vessels entering the Weser, to defray the cost of providing the safeguard. The undertaking was somewhat formidable. The shoal, being of soft sand, was liable to erosion and movement, owing to fluctuating and changing currents. Then, again, the proposed site, some thirty miles from Bremerhaven and about halfway between that port and the island of Heligoland, was exposed to the assaults of the North Sea, where even slight breezes ruffle the water considerably. From the soundings and observations that were made, it was evident that the foundations would have to be carried down to a great depth, and that ordinary systems of construction were quite impracticable. At this juncture the Society Harkort of Duisburg, which had accumulated great experience in subaqueous work, was approached and asked if it would undertake the enterprise at its own risk. This was tantamount to a “no cure, no pay” proposal. If they succeeded, they would be rewarded for their labours; if they failed, they would have to face a heavy loss.