Engineering Wonders of the World
Volume III

72 ENGINEERING WONDERS OF THE WORLD. WEST END OF THE ISLAND BREAKWATER, DOVER HARBOUR, SHOWING GRANITE MASONRY FACING OF THE BLOCKS. total quantity of stone required. In deference to the critics, but against his own convictions, he altered the seaward slope to 1 in 3. In January of 1817 severe gales . raged for several days. As justified by , J Storms soon as t ie weather permitted the ridge to be examined, it was found that a considerable part of the slope had been converted from 1 in 3 to 1 in 5 by the waves, which had flung great blocks of stone over the crest on to the lee- ward face. In spite of this object lesson no alteration in the plans was made, and the work went on as before. John Rennie died in 1821, long before his greatest enterprise in marine engineering had been completed. An even more violent storm than that just referred to came in November 1824, and again proved the engineer to be right, by reducing the slope for a distance of 800 yards. The authorities therefore decided to follow Rennie’s original advice. The break- water was completed—but not until 1848—on the 1 in 5 slope, and, to prevent th© displace- ment of rubble at and above low-water level, the faces and top were protected by large blocks of stone carefully shaped and cemented and dovetailed together. During construction the width at top was increased to 11 yards, and at bottom to 133 yards. Altogether, the breakwater consumed 3,670,444 tons of stone and 22,147 cubic yards of masonry, the placing of which cost the nation a million and a half sterling. Yet the money was well spent, as the Sound is now well sheltered from the gales, even such waves as pass over the breakwater being so reduced in size that they interfere but little with the shipping inside. The Holyhead breakwater exceeds consider-