Memarhs on the lieport of the Water Commission. 6T 



had reached high water mark. Some of this might be washed 

 away, but much would be driven in to any remaining crevices. 

 To protect the outer slope of the dam against tic'al action sand 

 should be tipped in, leaving the water to wa^h it down to the 

 ordinary sea-beach slope. That slope once attained would never 

 be disturbed by the action of waves. Even if exposed to a heavy 

 surf it would not be more destroyed than the ordinary sea-beach 

 is, but at the site indicated only comparatively small waves would 

 ever beat upon it. On the inner side it is proposed to make a 

 similar slope of sand. It might not be necessary in the first 

 instance to make it at the same angle, because the river would 

 always be bringing down silt, and because the pressure on the 

 dam would be more outwards than inwards, except in the case of 

 such a drought as would reduce the height of the fresh water 

 below the level of the salt. A dam thus constructed, with its 

 core of stone flanked on either side with a broad padding of sand, 

 would be immovable either by the pressure of the river on the 

 one side or the pressure of the highest tide on the other. As 

 the dam will be used as a high road for crossing the river, and 

 perhaps ultimately for a railway, it would be desirable to have it 

 not less than a chain wide at. the top ; and this roadway should 

 be sufficiently high to secure it from ever being under water. A 

 project somewhat nmilar in its main features is referred to in the 

 last edition of the ''Encyclopedia Britannica." "The noblest 

 attempt of the sort ever made in Britain was that of Mr. W. A. 

 Maddocks, in order to unite the counties of Merioneth and 

 Caernarvon by a mound across an estuary and embouchure of the 

 G-lasslyn, two miles wide. After consulting various engineers 

 the first operation was begun in 1807, and consisted in form- 

 ing an immense bridge of flood gates in the solid rock of the 

 shore, as such a bridge and gates could not be formed in any part 

 of the mound. The use of this was to admit the exit of the 

 river. This done, the mound was commenced from both shores, 

 and rocky, sandy, and clayey materials thrown down in the direc- 

 tion of the mound and left to take their own slope. The greater 

 part of these materials consisted of argillaceous rock, broken 

 into small pieces, which being mixed with clay the mound would 

 have been of the strongest texture. As the works proceeded, 

 an iron-railroad was laid along the top of it, and extended to the 

 quarries and excavations, by which means much labour was saved. 

 In the course of three years the work was brought within fifty 

 yards of meeting in the middle, but it was found extremely 

 difficult to close it, from the rapidity of the influx and reflux of 

 the tide. This difficulty however, would have been overcome and 

 the proposed improvement eftected at little more than the 

 estimated cost, £20,000, had not the various and extensive projects 

 in which the proprietor was at that time engaged led him into 



