COST OF DAMS. 367 



d. 



Inner dam deeper part 12 



Removal 300 



Per foot run 15 



Outer dam 21 10 



Removal 5 10 



Per foot run 27 



Outer dam circular part, with sliding-sluices 28 



Removal 700 



Per foot run 35 



Circular dam in steam-basin, to enclose new entrance (p. 73) ... 37 10 



Removal 3 10 



Per foot run 41 



Approximate cost of constructing the earthwork embankment across 

 the mouth of St. Mary's Creek, Chatham, consisting of materials 



taken from the excavations per foot lineal 11 15 3 



Average Proportional 



Dock Gates. Avonmouth Dock Gates 2 per price per 



cubic cubic foot 



foot. of timber. 

 *. d. 8. d. 



Cost of timber 2 5J 



Repairing and fitting 2 6| 



Erecting in place 1 1J 6 1 



Add for straps and bolts 1 11| 



Add for castings, including anchors, gate-sluices, two sets of 

 rollers to each leaf, pivots, and chain-roller boxes, but 



exclusive of all mason's work in fixing 25 4 4 \ 



Add for pumping, staff, and contingencies 1 OJ 1 OJ 



Total cost per cubic foot of timber 11 6 



Total cost of one pair of outer gates 



s. d. s. d. 



Net quantity of timber in one pair of outer gates 3 9710 @ 6 ] = 2973 13 9 



Ironwork .................. 9'710@4 4^ = 2113 18 11 



Pumping, staff, and contingencies ......... 9'710 @ I OJ = 49512 3J 



11 6 =5583 5 



5583-5 



Total cost per square foot of superficial area of back of gates = 1 5 4 J 



Or, taking the exact width between the copings, 70 feet by the 



height 48 feet = - , gives per square foot ......... 113 2| 



3360 



Dunkirk Dock Gates.* Mr. Guillain, the engineer of the 



1 M.P.I.C.E., vol. xxxi. p. 26. 2 Ibid., vol. Iv. pp. 20, 118. 



* Ibid., vol. Iv. p. 20, 118. 4 Ibid., vol. lix. pp. 26, 27. 



