a Goodwin Sand; had met with others eagerly reading up their “Murrays” at Blois to learn all about the grand levée de la Loire and the opposite embankments, which preserve, or are intended to preserve, the adjacent flat country from those “grandes inondations” to which French geographers and periodical accounts in the public papers inform us that the Loire is subject; we had met other travellers fresh from Russia who were in ecstatic raptures with the granite embankment of the Neva at St. Petersburg; Italian tourists who related impossible things about those of the Tiber and the Po; and pertinaciously patriotic Yankees who ‛guessed’ that the hundreds of miles of embankment, which protect the rich alluvial sugar-cane grounds on both banks of the Mississippi, ‘flogged’ everything of the sort in the Old World; but among all we found a Cimmerian darkness of mind; in short, an utter vacuity of all information whatever about the extent, nature of construction, and wonderful meanderings of the artificial banks of our own river.
A careful inspection—compasses in hand—of the Ordnance Survey Map first threw any real light on the subject; and it is well worthy any one’s while, who proposes to set about understanding and appreciating it, to begin in the same way. The map will reveal that the basin of the Thames, between London and the Nore, consists of a long and very irregularly-shaped flat, lying between high grounds, which sometimes, as at Purfleet, Greenhithe, and Northfleet, come quite up to the river itself, and sometimes recede for miles up into the country, as at Pitsea, where the basin is seven miles in width, of which the river itself occupies little more than one. The map further shows that the river is prevented from periodically or occasionally covering the whole of the floor of this basin by a system of embankments which extend, with occasional interruptions by highlands or houses, from Fulham and Putney above bridge down to the sea, a distance of upwards of fifty miles; and, though the map cannot show it, it will be well to bear in mind that a great extent of the river-side streets and houses form, in effect, part of the system of embankment—most of Southwark, Lambeth, Deptford, and Greenwich on the one side, and of Shadwell and Limehouse on the other, lying below the level of high-water spring tides, and being, in fact, all afloat whenever the tide flows higher than usual. The long, straggling street at Millwall presents a good specimen of this sort of embankment; for, in walking down it, it is impossible not to be aware that it is constructed on artificially raised ground, from which one looks down on the Thames on one side and the flat of the Isle of Dogs on the other: indeed, the very name of the place, or rather its termination, is suggestive, the title of “wall” being—both in Kent and Essex—universally applied to the embankments; and the names “Millwall,” “Blackwall,” “Rotherhithe-wall,” “Narrow-wall,” “Broadwall,” all denoting either places built upon the embankment, or streets which owe their existence to its protection.
However, this long double line of river wall, which follows the course of the bank on each side, forms but part of the system. Again referring to the map, it will be seen that the marsh-lands on each side are intersected by tributary streams and creeks, and a moment’s consideration will elicit the reflection that every one of these must also be banked on each side throughout the whole of its course through the flat country, and until land of a higher elevation than the highest spring tides is attained, or of course the water would, as the tide rose, steal round the back of the principal embankment by the channels of these creeks and tributaries, and render them simply useless. Indeed nothing will tend more to a due conception of the importance of every yard of these enormous works, than the reflection that the failure of the smallest portion of any part of them tends instantly to the destruction of the object of the whole: it is like the springing of a leak in a ship, or the snapping of one imperfectly welded link in a chain-cable. The failure itself may be trifling, but its consequences are almost illimitable.
Where, as in the instance to be presently adduced, the creek, or tributary, winds considerably, or branches out into many ramifications, the subordinate or auxiliary system of embankment adds many miles of river wall.png){kind=spacer}
Plan of the Creek at Holy Haven.
