The New Student's Reference Work/Breakwater

Breakwater, a bank or levee of stones or a timber structure, used to break the violence of the sea in its entrance into a harbor or roadstead.  There may be a natural breakwater, as the Isle of Wight, which protects Portsmouth and Southampton.  The Romans made artificial breakwaters of some size in several Italian ports.  The first modern structure and the greatest of all breakwaters is that at Cherbourg, on the French side of the English Channel.  There are also breakwaters in the English harbors of Plymouth, Portland and Holyhead.  Several structures of this kind have also been built upon the Great Lakes, as at Buffalo and Cleveland on Lake Erie and at Chicago on Lake Michigan.  The one at Buffalo is the largest in the United States.  The usual method of building breakwaters is to cast down large stones and allow them to settle under the action of the tides and currents.  The top is then covered with large blocks of artificial stone or with paving laid at a regular slope, and a wall is built.