The succeeding spring brought a resumption of toil, and by September the tower was completed except for the illuminating apparatus. One feature was observed during construction and had to receive attention. The free swing of the currents and tides, being obstructed by the tower, had commenced heavy erosion, big hollows being scooped out of the soft sea-bed around the caisson. As it was quite possible that in the course of time this scouring might imperil the safety of the building, protective works had to be undertaken. These were of an elaborate character, and comprised the sinking of mattresses, fashioned from brushwood, around the foundations, upon which were dumped boatloads of broken stone. This mattress had to be nearly 50 feet in width, and in some places about 15 feet in thickness. For this protective work alone some 176,550 cubic feet of brushwood, and 600 tons of block-stone to hold it down, were used. These measures, however, effectually overcame the danger of erosion. On November 1, 1885, the light was shown for the first time, and the greatest peril at the entrance to the Weser was indicated far and wide by night and day. It was a magnificent achievement, carried through in the face of enormous difficulties, sensational incidents innumerable, and upon a foundation of disaster. The lighthouse is as firm as if it were anchored upon a solid granite rock, instead of having its roots thrust deep into treacherous shifting sand, and constitutes an imperishable monument to German engineering ability; while, all things considered, the cost was low, being only £43,400, or $217,000, in all. The light is electric, the power being supplied from a station on shore, and fed to the lighthouse through a submarine cable; the keepers are also in submarine telegraphic communication with the mainland. When the United States set out to build a similar structure in the spacious Delaware Bay, they were confronted with a prospect just as forbidding, and a task in every way as difficult, as that offered in connection with the Rothersand. There is a dangerous shoal about twenty miles off the land, where the Atlantic beats with furious rage, and where vessels were apt to stick hard and fast. It was described as “Fourteen Foot Bank” by mariners, from the depth of the water flowing over the shoal, and this colloquialism has provided the name for the present guardian light. The open situation did not augur favourably for the completion of a lighthouse at this spot, but the American engineers were resolved to make the attempt. Accordingly, plans were prepared for a construction upon the caisson principle, which was the only method promising success.