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DOCK ENGINEERING.
wall of 42 feet 10 inches. The coping is of granite in blocks of from 2 to 4
tons weight. The profile of the wall is shown in fig. 146.
The cost of a quay wall constructed in this way and to these dimensions
came to £40 per foot run, including 7 per cent, interest on a sum of
£33,800 for plant. The rate of construction was 400 lineal feet per annum.
On the same principle, but with blocks of smaller dimensions, a quay
wall (fig. 147) some 500 yards in length, was constructed at Cork about the
year 1877.* The submerged portion of the wall consisted of three rows of
blocks, rectangular in plan, weighing from 35 to 49 tons each. As in the
case of the Dublin blocks, they were constructed at a wharf some distance
away and transported to their respective positions by a floating sheers.
The composition of the monoliths, however, was different, in that they
were made entirely of concrete in the proportion of 7 to 1—viz., 5 parts
river ballast, 2 parts broken limestone passed through a 3-inch ring, and
1 part Portland cement.
Fig. 147.—Quay Wall at Cork.
Fig. 146. —Quay Wall at Dublin.
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The foundation consisted mainly of fine compact gravel and sand. After
being dredged to within 2 feet of the required dépth the remaining material
was removed by divers. A rectangular frame of angle iron slightly larger
than the block was then laid on the ground and adjusted by soundings from
above. The surface inequalities within the enclosure were levelied by an
iron straight edge.
The blocks (figs. 148 and 149) were suspended by four stirrup-rods pass-
ing down vertical grooves, 10 inches by 5 inches, in the sides of the blocks,
* Barry on “ Deep Water Quays at the Port of Cork,” Min. Proc. Inst. C.E., vol. c.