Engineering Wonders of the World
Volume III

70 ENGINEERING WONDERS OF THE WORLD. The Cherbourg Digue. is taken chronologically and otherwise by the immense digue protecting Cherbourg Harbour. It was begun in the time of Louis the Fourteenth, and after being severely damaged and repaired several times, was finally reconstructed in 1832. Its total length is 4,120 yards, or about 2| miles, making it and topped by a wall of granite masonry. The wall is protected on the sea slope by blocks deposited “ random.” Th© great breakwater in the entrance to Plymouth Sound owes its existence to the genius of the famous engineer, John Rennie. In 1811 an Order in Council was issued allow- ing Rennie to commence the gigantic task of A BLOCK-MAKING YARD, DOVER HARBOUR WORKS. Some of the concrete blocks weigh over forty tons each. the longest single breakwater in the world. It consists of two arms, 2,441 and 1,679 yards long, forming with each other an angle of about 170 degrees. At each extremity, and at the point of junction of the arms, pro- vision was made for a large circular fort. This remarkable mole shelters an area of nearly 2,000 acres, being assisted by a 500- yard breakwater running out from the shore towards its eastern end. As it stands to-day, the digue consists of a rubble bank faced with a thick blanket of hydraulic concrete, forming, with stones deposited from barges, a dike a mile long, 55 yards wide at th© base and 10 yards wide at the crest. The breakwater was to be Plymouth . . J _ , , Breakwater. quite isolated, and have a straight central part 1000 yards in length, with terminal wings, each 350 yards long, inclined at a very obtuse angle to the main portion. Rennie’s method was to dump the stones in mass along the line of the breakwater, and to allow the waves, which, he declared, were the best possible workmen obtainable, to move the