Essex coast, the prevailing set of the current is completely reversed by the relative spaces this vacancy brings into juxta position in connexion with land streams. Canvey Island, Foulness, Stone Point, and the site on which Harwich stands, together with the general line of shore, evince a prevailing north-east current. The sand banks of the Nore uniformly take a consimilar course. Running off with the north and south line of Southwould and Orfordness. But the Goodwin Sands, the little Bank, and Calais Bank, off Dover and Margate, assume the north and south range of the North Sea, and conform to its general current. Nor is it a little remarkable that these several sand banks lie immediately on the entrance to the Strait of Dover. Why? In the north Irish Channel nothing similar is found, because it is a tidal thoroughfare. Here a counteracting tide-wave obtains. The tidal currents of the North Sea and the British Channel meet in the Strait of Dover, and repel, and have repelled each other on this ground now and formerly. The balance of prevailing winds may incidentally shift the contact of these tidewaves, westwards or eastwards, but the Strait of Dover is the true central point on which they balance each other. Romney Marsh is also a deposit attributable to this tidal meeting; and a balance of currents is contributing to close up, and not enlarge the Strait of Dover, where we might have expected that rocks themselves would scarcely hold their place. Even the chalk hills of Kent, Sussex, Surrey, and Essex, are all of them depositions, and consequences of the same balance and terminus of currents. In the north Irish Channel no sand banks, rocks completely denuded, and eighty-eight fathoms of water in the centre of the Channel, are met with At the Strait of Dover thirty fathoms is the deepest water met with, the most shallow line of water between Great Britain and foreign shores. All drifted silt which enters the North Sea necessarily remains there, and contributes to obstruct navigation. In truth, the Strait of Dover has a natural tendency to silt up, may possibly do so in time, and such an event happening there would be no likelihood of its breaking down again. For it is what has previously occurred in the basins of London and Paris, each of which lies in the same line of oceanic contact, The reason why France and England are brought so near each other at the Strait of Dover, is owing to depositions from the coast of Norway and the south of Ireland being driven here and remaining. Why do we find Romney Marsh? Why are dry sand banks found at ebb-tide all but in the Strait of Dover? Why is 30 fathoms of water only exhibited in the southern parts of the North Sea? What a contrast to the coast of Norway! As much as 200 fathoms prevail close in shore. Conclusive facts evince the truth of what has been said before. The North Sea is but a point to which deposi tions, which lie extended 2000 miles eastwards, and 1500 in breadth, have arrived. The very Atlantic and Polar deeps have been scoured out to find material for a territory so enlarged. In short, to this hour, the very rocks of Norway are daily ground away, and the silt so produced is driven into the North Sea, or deposited on its shores ever to remain. We shall now proceed to the application of these premises. In closing the chapter before us, however, it may be observed that a shelving beach is a usual form of the shores of the sea. Hence the ordinary position of stratified rocks is that of a slope carried out to its extreme angle. On such grounds Mr. Fairholme justly infers that projecting cliffs have had their original elongation cut away by the action of the sea in cross currents. On this head the student in Geology may obtain much satisfactory information from his work on the Mosaic Deluge. THE RECLAMATION OF LAND FROM THE SEA, THE rise of tides upon our shores is here a primary consideration. The North Sea, the Irish Sea, the British, Bristol, and Saint George's Channels, having no rise of tides intrinsically within themselves, derive their tidal phenomena from the Atlantic Ocean. Thrown off by the returning gulf stream in its southern course, these tides are necessarily regulated by one common impetus and volume of water. Every difference in tidal elevations witnessed on our shores, must therefore be sought for in other causes than the primary tide, which may be taken as equal in the distribution of its waters. Lunar influence acting by the force of gravitation on the body of water contained in the Atlantic, being the original seat of tides on the shores of the British Isles, and the north of France, the flow and ebb of those mighty waters, though we have assigned them nine feet in spring tides, and six feet in neap tides, at the Blaskets, yet the flow and ebb of the Atlantic itself may not exceed three feet in spring, and two feet in neap tides. Whether lunar influence withdraws or augments the force of gravitation on a body of waters so extended and deep as these are known to be, an elastic bound so mighty in the depth of impulse, naturally imparts a higher tidal elevation proportionally as it runs on shallow and limited shores. At the Blasket Island, therefore, on the west coast of Ireland, the ordinary rise of spring tides is 9 feet, in Bantry Bay 11 feet, and Youghall the same, at Waterford 13 feet, and in the Irish Sea 20 feet. In the north Irish Channel the rise of spring tides is 11 feet, at Belfast the same, and in the northern section of the Irish Sea 26 feet. But in the Pile of Fowdry, where the tides of the north and south Irish Channels meet, the rise of tides is 30 feet. Tracing the tidal rise in the British Channel, beginning at the Blasket Island it is 9 feet, in Bantry Bay 11 feet, Falmouth 18, Eddystone Light House 18, Sturt Point 20, Yarmouth 12, West Cows 15, Southampton 18, Spithead 18, Selsey 15, Brighthemlstone 16, Beachy Head 20, Dunge Ness 24, and Folkstone 22 feet. On the coast of France, opposite to Falmouth, the rise of tide is 20 feet at Ushant, Isle de Bas, 27, Morlaix 30, Isles of Brehat 36, Cherbourg 20, La Hogue 16, and at Havre de Grace 23 feet. In tracing the tidal rise from the Blaskets, up the Bristol Channel, at Cape Cornwall, it is 22 feet, Saint Ives 24, Pad |