A breakwater, we are told on the highest authority, is an obstruction of wood, stone, or other material, as a boom or raft of wood, sunken vessels, &c., placed before the entrance of a port or harbour, or any projection from the land into the sea, as a mole, pier, or jetty, so situated as to break the force of the waves and prevent damage to shipping lying at anchor within them. Thus the piers of the ancient Piræus and of Rhodes; the moles of Venice, Naples, Genoa, and Castellamare; the piers of Ramsgate, Margate, Folkestone, Howth, and the famous wooden dike thrown across the port of Rochelle. The term, of late years, has been almost exclusively applied to insulated dikes of stone. Of this description of dike for creating an artificial harbour on a grand scale, Cherbourg, Plymouth, and Portland present leading examples. The former, already mentioned in this work, claims our attention. The French, happily our good friends to-day, were not always so, and there was a period when the splendid natural harbours, bays, and roadsteads of this country were a source of annoyance to them. While nature had been more than kind to us, their coast presented a series of sandy shores, intermingled with iron-bound coasts, bristling with rocks. De Vauban, the great engineer, was employed by Louis, the _Grand Monarque_, to inspect the Channel shores of France, and his natural sagacity and great knowledge caused him at once to select Cherbourg as one of the best points for forming an artificial harbour, protected by suitable fortifications. Other engineers recommended the same port, and one, M. de la Bretonnière, proposed that a number of old ships should be loaded with stones and sunk, while a large quantity of stone should be also thrown around them to form a grand breakwater, which should rise fifty feet from the bottom. This idea was abandoned, as it appears, partly from the fact that France had not old vessels enough to spare for the purpose, and that it would cost too much to purchase them from foreign nations.