A Treatise On The Principles And Practice Of Harbour Engineering

42 HARBOUR ENGINEERING. viaducts, wooden or composite, from 330 feet to 660 feet long, lead to the shore, and are divided into from thirteen to twenty bays, which span openings from 20 feet to 30 feet wide. On the coast of Denmark, tides are insignificant, hardly perceptible in Fig. 39. —Plan of Hundested Island Harbour. the Baltic, not exceeding 1 foot in the Cattegat, and rising only to 4 feet 6 inches in the North Sea near the Southern Boundary. Hence, any movement of material which takes place is not due to tidal action, bat to the action of the waves, com- bined, perhaps, with that of local currents, and, whichever of these agencies be considered, attributable to the effect of the wind. The object aimed at by the three fishing ports seems to have been accomplished fairly well. At neither Arnager nor Snogebæk has material accumulated to an alarming degree ; it is pure quartz sand, the size of the grains being ’45 and '25 mm. respectively. At Hundested the drifting material is more hetero- geneous, consisting of a mixture of quartz sand with grains of ’25 mm. in diameter, gravel, shingle, larger pebbles, and good-sized boulders. Some accumulation has taken place inside the 5 m. contour, and banks have formed at the south-east mole and at the shore south-east of the port; but a state of equilibrium seems to have been reached, in which these two banks play an important part.