The encyclopdia britannica; a dictionary of arts, sciences, literature and general information . achine. The front Goliath was used for working a grab for ex-cavating the surface layer of chalk, which was finally levelled bydivers, the second for carrying the diving-bell, the third for layingthe blocks below low water, and the fourth for setting the blocksabove low water. This succession of Goliaths enabled more rapidprogress to be made than with a single Titan at the end of a break-water ; but it involved a considerable increase in the cost of the plant,owing to the temporary staging required
The encyclopdia britannica; a dictionary of arts, sciences, literature and general information . achine. The front Goliath was used for working a grab for ex-cavating the surface layer of chalk, which was finally levelled bydivers, the second for carrying the diving-bell, the third for layingthe blocks below low water, and the fourth for setting the blocksabove low water. This succession of Goliaths enabled more rapidprogress to be made than with a single Titan at the end of a break-water ; but it involved a considerable increase in the cost of the plant,owing to the temporary staging required. The foundations werecarried down from 4 to 6 ft. into the chalk bottom, the deepest being53 ft. below low water of spring tides, and the average 47 ft. Witha rise of tide at springs of i8f ft., the average depth is thus approxi-mately 66 ft. at high tide, necessitating a pressure of 29 lb on thesquare inch, which is the limit at which men can work without in-convenience in the diving-bells. The breakwaters are raised about11 ft. above high water of springs. The detached southern breakwater. Fig. Breakwater. Scale 80o. Dover Breakwater. Fig. Pier Extension,was finished off at this level; but the extended western breakwater,or Admiralty pier, is provided with a promenade parapet on itsexposed side, rising 13 ft. above the quay; and the eastern break-water also has a parapet on its exposed eastern side, raised, however,only 9 ft. above its quay. The breakwaters are protected from scouralong their outer toe by an apron of concrete blocks, extending 25 from their sea face. The levelling of the foundations for laying the courses of anupright-wall breakwater is costly and tedious, even in chalk; andthe expense and delay are considerably enhanced where _ ,the bottom is hard rock. Accordingly, in constructing Z^^two breakwaters at the entrance to Aberdeen harbour %f„ja-on a bottom of granite in 1870-1877, concrete bags were t,„„g_laid on the sea-bed;
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectencyclo, bookyear1910
