At Eastbourne, about two years age, I made acquaintance with a phenomenon in this line which was altogether new to my experience. We had a tremendous gale late in the autumn of 1857. I cannot exactly cite the quarter from which the wind blew, as I do not accurately know the points of the compass in their bearing on the town and bay; but the storm seemed to beat in from the south-east, as it faced the Marine Esplanade. I went forth, with perhaps a score of others, to gaze upon this magnificent “encountering shock” of earth, air, and water. We were all of us drenched to the skin by the dashing spray, and occasionally well-nigh swept off our legs by the gust; but we held on stoutly, till something saluted those nearest the beach, which rendered a retreat imperative. This was not the salt spray, nor the rattling hail neither, but a cloud of “skirmishers” in the shape of pebbles and gravel from the strand below. The sea had actually lifted the surface of the bed of beach, and whirled aloft some bushels of its solid contents. A coast-guard told me next day, that he saw a “flight” of pebbles, some of them as big as hens’ eggs, at least thirty feet high in the air; and he added, that if the direction of the wind had changed a little, every pane of glass on the ground and first-floor of the Esplanade must have been shivered to atoms. As it was, of course much damage was done to windows and sashes; but not by the actual pebbles.
After this gale had subsided, I ascertained by personal inspection that some hundred tons’ weight of solid shingle had been moved along the shore a distance of a quarter of a mile, in the space of a few hours. This was by the sidelong drag of the tide.
The village of Seaford, on this same line of coast, had long been in great danger of being swept away by the tide. Its outworks and very standing ground were perceptibly yielding, season after season.
About eight years ago, the inhabitants took the alarm, and drew up a remonstrance and petition, which were duly forwarded to the authorities. Proper officers were deputed to go down from London and report; and the result of their representations was that an able engineer from head-quarters was empowered “videre ne quid Respublica detrimenti capiat;” or, in the modern vernacular, to see that the Queen’s lieges in Seaford suffered no wrong.
The remedy hit upon was simple and forcible; but, assuredly, it was an instance of what is called “Hobson’s choice.” The engineer said, “There is only one thing to be done; a solid breakwater must be formed west of the town, to break the rush of the sea and divert the course of the current. We will throw down a section of the chalk-cliff; that will make a mound, on which works of masonry, if necessary, can be erected afterwards.”
This was done about two miles east of Newhaven, by firing an enormous charge of gunpowder in chambers drilled in the limestone. I went over from Brighton to witness it, and the sight was a striking one, as soon as the smoke and dust consequent on the explosion had cleared away. The operation, neatly conducted with an electric battery, proved successful; and its result, in the amount of chalk thrown down on the beach, was judged sufficient for the time.
But for this “pièce de resistance,” Seaford might by this be in a fair way to furnish to future generations a gigantic specimen of a marine fossil.
The danger to Seaford arose not from storms or any casual visitations, but from the steady continuous action of the tide encroaching on the line of coast where the town stands. Whether the chalky breakwater above described will long suffice to counteract this elemental mischief may be doubted. If after a while it should prove inadequate, the operation will have to be repeated on a larger scale.
The height of the tides at sea is always known; and it varies little, depending upon astronomical causes, chiefly on the attraction exercised by the moon. But on shore, and inland in certain rivers, the case is widely different. Here the land itself, with its rocks and embankments, introduces artificial conditions which influence the local tides in an extraordinary manner. Thus, at Chepstow, by the Castle rock, the rise of a spring-tide is sometimes as much as sixty feet perpendicular. In Mount’s Bay, Cornwall, it is fully forty feet; while in the north of Scotland on the coast, it does not average more than ten.
The tides have other variations beside this of local magnitude; and one of these, which takes place along our southern coast, is interesting and important, but was little known till the Admiralty surveyors went to work. It may be briefly described as follows.