Harbors

Artificial harbors are built at the mouths of rivers by the construction of jetties, breakwaters, and basins, in order to form a safe refuge for shipping. The figure gives a general view of the new harbor at Boulogne, France, which was begun in 1878. On the right is a breakwater 5,700 ft. long, forming a sheltered haven with dock landings near the shore. On the left are two small parallel jetties, forming the entrance to the inner harbor and inner basins. The cost of the jetties was $5,000,000. The inner basins of such harbors are usually Harbor at Boulogne, France. provided with gates which are opened only at high tide; such basins with their laterals may often accommodate hundreds of ve els. IMG:content-0491.jpg:[ocr errors]