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erected for the purpose of collecting or preventing the denudation of the sand from the beach consist of a layer of mattress-work made of willows secured in place by piles. This is used for the purpose of preventing the stones sinking into the fine sand. On this mattress-work is placed a layer of rubble basalt about 18 inches in thickness. These groynes extend to some distance below low water, certain lengths reaching at Scheveningen to 325 yards, the average length being about 120 yards, and the full width 40 feet, the distance apart being a little more than that of the length. The willow mattress does not last longer than about twenty years, and consequently the groynes frequently require reconstruction. Similar groynes are used on other parts of the coast. On some of the groynes the piles project above the shore as much as 6 feet. There is a strong controversy as to whether this does good or harm, the more general modern opinion being that they are injurious. In addition to their uselessness, these piles, projecting above the beach over a wide area, are a great eyesore and give a dismal appearance, and tend greatly to destroy the beauty of the shore where they are used in front of a watering-place. In some cases these groynes collect sand or raise the beach, but their general effect is only to prevent denudation. Where the beach is steep, say at an angle of 1 in 25, they are most effective, but when the slopes reach 1 in 50, little or no accretion takes place.

At West Kapelle, the groynes for the protection of the coast of the Island of Walcheren, and more particularly of the sea-bank between Domburg and West Kapelle, are of a very substantial character. They vary in length, the average being about 130 yards, the maximum distance apart being 300 yards. They consist of from two to four rows of fir piles, 8 inches in diameter, 12 to 18 feet in length, and projecting 6 feet above the beach, driven from 6 to 8 inches apart. They are connected by walings on each side, and divided into bays by cross-timbers. The space between the piles is filled with clay, brushwork, and stones, some of these being 2 feet square. They rake at a broken slope, the angle varying from 1 in 23 near the bank to 1 in 35 further out. At the end of each groyne mattresses are placed 130 feet in length. The piles formerly were studded with worm nails to 6 feet below high-water level, having broad flat heads, the rust from which stopped the action of the teredo.

At Schleswig and Holstein the sea-dykes are protected by

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groynes, which run out a long way across the sands. Experience has shown that when these groynes extend only a short distance, although they are serviceable in preventing the beach from being hollowed out, they do not lead to any accumulation of sand. When they are extended outwards from 430 to 560 yards they afford practical protection to the sea-wall, and cause a rise in the upper part of the beach. These groynes are from 2 to 3 feet high, made of mounds of earth covered with grass and matting, having a top width of 4 feet, with slopes of 4 to 1 on the windward side and 3 to 1 on the lee side (Min. Proc. Inst. C.E., vol. xxi.).

On the north coast of the Island of Schouwen, for the purpose of preventing the waves from the North Sea forming deep lows close to the shore and endangering its safety, groynes were placed at right angles to the coast, spaced 164 yards apart. These were constructed of layers of fascines covered with stones and fastened down to the beach with oak staves. The result was satisfactory. The cost of maintenance of from 18 to 25 groynes between the years 1872-86 was given as £5703, equal to £19 a year for each groyne.

For the purpose of protecting the coast of Mecklenburg near Rostock, and to keep open the entrance of the Warnemunde by trapping the sand drifting along the coast, and thus creating a beach, groynes spaced 1 times their length were erected in 1889, for a length of 2 miles along the coast, and carried to a depth of 8 feet. They consisted of piles 8 inches in diameter driven 31 feet, and pitched in two rows 2 feet apart. Fascines were packed between the piles, and secured by transverse timbers and walings. The piles at the end of the groynes were sunk 5 to 6 feet, and the fascines weighted with stones. The result was quite successful, the drift of the sand, which is very fine, being stopped by the fascines, and a beach formed 55 yards wide and to a depth of 63 feet.

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