EDWARDS, (Read before the Asiatic Society 5th August, 1864.)
The sea wall commences half a mile to the south of the South-east gate of Hang-chow, and along the bank of the river Tsiea-tang, which here becomes an estuary, past Hai-ning to a hill called Tien-shan, a distance of thirty.
i partakes more of the form of a bund or earth embankment, and as such passes along the coast to Hai-yen, Chapa, &c., to the mouth of the Yangtze, Tatter part'still remains in good order and is not s0 liable to be destroyed as the part first mentioned, The river Teien-tang- opposite Hang-chow expands into an estuary and becomes a bay at Tien-shan. Ibis eataary is very shallow and at low water nearly dr The ebb) tide runs down for ten hours, at ate of frum 8 to 10 miles an hour. The flood a bore or wave varying in height, but gener-eminences opposite Tien-shan in the form of ally 4 or 5 feet, which passes up the estuary at the rate of 12 or 15 miles an hour, breaking with great force against the sea wall. Ina few seconds the tide rises four or five feet. At certain times of the year, about the 8th of the 8th moon, the people from the neighbourhood of Soochow and other places come to feo the bore, which is reported to flow in at this time with very grt loco.
The wall from Hang-chow to Tien-shan is constructed to keep out the sea at high water, which would otherwise inundate the surrounding "country. Spring tides here rise About a foot above the surrounding country the level of which is considerably higher than. that of the country around Shanghai, as is shown by water running down into the Hwang-poo river.
The rise and fall of the tide near Kan-ptt is 40 feet, whereas at Woosung itis only 18 feet. at the head of Hang-chow Bay than at Woo. Consequently the water rives 124 feeb higher
only 7 feet, which is due to the slope li song, Nest Hangchow the rise and fall ie he bed of the river Tsien-tang. As the tide at the head of the estuary rises at least to the same height that it does at the mouth near Kau-pit, it follows that high water mark there 194 feet higher than at the month of the Hwang-poo river at Woosung. However at Woosung the tide does not rise to within two feet of the level of the country, whereas at Hang-chow it rises one foot above it, From this we deduce the level of the country at Hang-chow to be 13} feet above that of the country at Woosung, the distance between the tivo points being about 96 miles.
The wall is 6 feet thick at the top, and 12 feet at the bottom, having the same slope front and rear, andis in most places about 20 foot high. "It is built of limestone quarried near Shaou-hing on the opposite side of the bay. The stone in very hard and durable, and is cut into pieces about four fect in length and one foot in width and depth. It is built on a foundation of piles and backed up with earth 40 feet in thickness, To preserve the wall from the effects of the sea and currents, bank built with earth and fascines and piled in front has been formed in many places front of the masonry wall.
Within #) ea wall is an interior bund of earth ata distance of from a few hundred yards to one milo from it, This has existed generally throughout, but between Hang-chow and Haining it does not appear to have been kept in repair for a very long time, and for a considerable distance no traces of it are left, From Hai-ning to Tiew-shan it is in good repair.
'The country in the vicinity of this wall has been occupied by the rebels for the last four et' and it-is owing to their not having opt it in repair that great portions of it have been destroyed. The part most seriously affected is that in the neighbourhood of Hai ning. Towards the cast it-is partially stroyed for six miles. There are many gaps in it some 500 and 600 yards in length. Here the water from the estuary is prevented from getting into the creeks by the inner bund, which is now unbroken, and no pains should be spared to maintain it To the westward of Hai-ning towards Hangchow the wall is not materially dai for the first 5 miles, but there area few small gaps. Paming along still to the westward, the next 4 miles present a series of gaps of 400 to 500 yards in length. Immediately be-we came upon a break of not less than 000 yards in length where the wall has been completely obliterated. Beyond this, however, there are only afew small breaks of minor importance, It is from this large gap of 2,000 yards and in those immediately preceding it, that the water now finds its way into the creeks, and inundates at high water come 60 square miles.ef- the surrounding count Thence it penetrates to Shu-mun on Grand Canal, and afterwards reaches Hwang-poo, but as that derives its water from the Tai-bu which flows into it through many creeks and small lakes south-east of Soochow, as well as from the hills and country near Hang-chow, it is evident that so large a body of water can only be very slightly affected by the emall quantity of brackish water whic enters it through the breaches in the sea. wall above described, This circumstance need not therefore awaken any apprehension as to the waters or, vegetation around Shanghai Immediate steps should homeyer. be taken to rceptibly affect y brackish water.
repair the inner bund. This could be accom:
ished in a short time if sufficient means e employed, at an expense of one hundred thousand tacle.:
about the destruction of the outer wall, in-'The principal causes which have brought dependent of those arising from ite not having been kept in a proper state of repair for the last four years, ar Jat.—Faults of construction, 2od.—Tho undermining action of the currents of the river, Srd.—Want of protection from the action of water at the book of the wall, With reference to the first, there are three faults of construction The wall i it without counterforts, and consequently" wanting is solidity and strength.
The lowest course of stone is not carried sufficiently below low watermark, which often allows th ster to act under it at low water.
The piles on which the wall reste are not of sufficient size or strength, and consequently the foundations youre, The undermining action of the currents la the most difficult to deal with. It tends to bring down the angles of the wall, and more efficient means should be used to guard against this by employing stronger piles and heavier masses of stone at the foot of the wall, constant to keep it always in a state of rep:
The remaining cause, vi from water acting at the back of t om the want wall, ari of proper "'puddling." This is one of the most important things to be attended to, bee cause in most, instances the wall has. been brought down by this cause alone, from the water working its way ander it, and in course of time carrying away its foundations,
Text read from the printed page and cleaned; old type leaves the occasional error.