Pozzolano.—As the lime used in the barrage was fat lime, it was necessary to make artificial Pozzolano, which came to 45 piast. (11 fr. 25) the cubic metre. This Pozzolano could not be used for sea work, for we are convinced by experience that it is affected by the magnesia which is found in sea-water. It can, therefore, only serve for the works of the canal of communication, and, like the bricks, it will cost less than at the barrage.
For the sea masonry, we have happily discovered solid masses in the harbour of Suez, anciently formed at the time of the Caliphs, or more probably at that of the Ptolemies. These masses of masonry are so compact, that when fragments are detached, the stone breaks more easily than the mortar, which is simply composed of sand and hydraulic lime.
This lime very probably comes from the mountains of Ataka, which contain several beds of calcareous marl; and there is no doubt that, by making researches, the beds that supplied the hydraulic lime may be discovered. Samples have been sent to M. Leplay, chief engineer and professor at the School of Mines, for analyzation, and more will be sent until good beds shall be found.
On this supposition, it is more than likely that the masonry of the Maritime Canal will be less expensive than that of the barrage, since it will be enough to have hydraulic lime to mix with the sand, which is found at all points of the Canal.
Timber.—The timber will come from Anatolia and Caramania. Oak and fir planks will be procured from Trieste. These materials will not cost more than at the barrage; for, though the distance of inland transport is greater, the expense of trans-shipment will be avoided by the construction of a new lock, which will unite the Mahmoudieh Canal, and consequently the Nile, with the sea.
Iron.—It will be the same with regard to wrought and cast iron, which will be procured from England and Russia.
Now, the barrage of the Nile is 1006 metres in length, with four locks, of which two are double, of 12 metres opening, and two others of 15 metres. It is established upon a general platform at 7 metres below the low water, is 46 metres wide, and four metres average thickness, with two lines of jaunting piles, and 1600 metres of quay walls, and only cost 18,000,000 francs, including the purchase of steam machines, to the number of twenty-two, the construction of all works and all the charges of administration, which were considerable.
If this amount is divided by the total length of 1006, 17,900 francs will be obtained for the cost of a running metre, including all the accessories of locks, quays, machines, and charges of administration.