Open main menu

Page:Popular Science Monthly Volume 72.djvu/232

This page has been proofread, but needs to be validated.
228
POPULAR SCIENCE MONTHLY

PSM V72 D232 The sea wall at haining at low water level.png

The Bore Wail at Haining, showing the Sea Foot.

average 250,000 taels per annum, which has led many people of this region to call this sea-wall "China's Second Great Sorrow," giving place to only the Yellow River as her "First Great Sorrow."

For purposes of management and repair the wall is divided into three major divisions with a superintendent over each. These divisions are again divided into many sections about a mile long, and for each mile there are at ordinary times four to six watchmen who patrol their section much as railroads are patrolled.

The first cost of construction must have been enormous, and the mere existence of the wall suffices to show that it must have been of vital importance and that the land it reclaimed and now protects must have been of immense value to justify such an expenditure.

As it exists to-day its total length is one hundred and eighty miles, and for one third of this distance it is faced, as at Haining, with heavy blocks of granite and varies from twenty-five to thirty feet in height above low water. Each successively higher layer of granite slabs recedes about five inches, thus forming steps, a very welcome arrangement when, after descending to get camera views of various parts of the wall just before a bore was due, we had hastily to retreat before the oncoming flood.

The main difficulty in maintaining an efficient sea-wall would seem to be to have an outer footing adequate to break the first violence of the incoming bore and to prevent the undermining of the foundations of the main bunding—in fact it would seem essential that the tides