RETAINING BASIN.—The semicircular dyke forming the retaining basin will have a developement of 6200 _met._ and the contents will be 890,000 _met. cub._ its cost will therefore be 13,500,000 The shingling on the banks of the canal for a length of 100 _kil._ is estimated at 1,500,000 QUAY WALLS OF PORT TIMSAH.—The quay walls to be constructed in the harbour of Lake Timsah, for a length of 1500 _met._ are estimated at 1200 _fr._ the running _metre_ (though we have constructed some entirely of hewn stone, which only cost 850 _fr._); the cost of this item will therefore be 1,800,000 In order to ascertain in a general manner whether the figures which we exhibit are in conformity with the data resulting from experience, we have examined the costs of analogous works, that we might compare them with those which we have determined. The dyke of Cherbourg, which is 3800 _met._ long, has cost 68,000,000, after all the vicissitudes it has undergone from the beginning of the century. It comes therefore to about 17,900 _fr._ per running _metre_. Its depth is 18 _met._, 80 below high water, while the average depth of those projected is only 4 _met._ Now if we assume, as is evidently correct, that the bulk, and consequently the cost of each, are as the square of its height, we find that as the dyke of Cherbourg cost 17,900 _fr._ the running _metre_, those of Suez should cost twenty-two times less, that is 815 _fr._ yet they come to 1790 _fr._ the running _metre_. The jetties of the harbour of Joliette at Marseilles, allowance made for all expenses, come to 5500 _fr._ the running _metre_. Their foundations are 11 _met._, 50 below low water. Those of Pelusium ought, therefore, to cost nine times less, that is 615 _fr._ The mole of the harbour of Valencia, which is 560 _met._ long, and the foundation 8 _metres_, 50, deep, was awarded for a sum of 3,000,000 _fr._: according to this price the defensive mole of Pelusium should cost less than that sum, while we have estimated it at 3,750,000 _fr._ The mole of the harbour of Cannes, which is only 150 _met._ long, has been estimated at 1,300,000 _fr._, which is 8666 _fr._ per running metre, but it goes to depths of water that reach 10 _met._: its cost is therefore, at least six times more considerable than that of the jetties of Suez; yet our estimate is more than the fifth of that figure. We may therefore say that our estimates are in excess as regards the works of Suez, and very much more so for those of Pelusium, since, in proportion, our figures exceed even those of works executed under the most unfavourable conditions.