THE NILE AND THE CROTON DAMS.
When it was determined to dam the Nile at Assuan, near the First Cataract, Sir John Aird, the contractor, undertook to complete the work for the Egyptian (more correctly, the British) government in five years. The work has been accomplished in a little less than four years But then the builder had placed at his disposal 15,000 fellaheen, the poorest of the poor Egyptian workers, who will labor on untiringly and be satisfied with a very meagre diet, and had, besides, all his material close at hand when he began operations. The foundation of the Assuan dam rests upon solid granite at the bottom of the river. Its length is nearly one mile and a quarter; its height above the bed of the river, ninety feet; its width at top, thirty feet; its capacity, 220,000,000,000 gallons. Its purpose is to regulate the supply of water for irrigation purposes. At present it is by far the greatest work of the kind in the world.
The Croton dam. the object of which is to supply water for all uses to New York city—the second in the world in point of size, was begun five years ago, and will probably not be completed in much less than six years, although the engineers who planned it assigned five years as the period within which it was to be completed. In its sectional forms it very much resembles the Assuan dam. In its details, however, there are many important differences. Its capacity is only 52.000,000,000 gallons; its height from the river bed is 150 feet—its foundation extending seventy feet below the level; its width at ton, eighteen feet: its length, hardly a quarter of a mile. Doubtless, had Contractor Coleman been able to set 15.000 Italians to work, instead of about onethird of that number, and found all of his granite ready to hand end a granite riv r bed for his foundation, he would have been able to finish his task very nearly within the specified term of five years.
The lowest level water ever reaches at Assuan is 279 feet above the Mediterranean. By means of the dam the water will he held up to 547.6 feet. To prevent the interruption of navigation a canal more than a mile long, and with four locks with steel gates, is in process of construction around the dam. The estimated cost of the reservoirs at Assuan and Assittt was $10.000.000: this has been much exceeded, hut how much is not definitely stated. The cost of the canal, about $1,250,000. is in addition to the above figures. The stone for the dam has Wen taken from the quarries that were worked under the Pharaohs, and the blocks got out bv the English contractors bear the marks of the tools of workmen who perished thirty centuries ago. The original plan would have submerged the temples of Philte and to save them the crest of the dam was drooped twenty-six feet, leaving the more important buildings above water, and reducing the amount of water that can he stored to something over one billion cubic metres. The dam will add nearly 1000,000 acres of desert to the arable land of Egypt. By its construction the Nile is closed to navigation: but the canal mentioned above obviates that difficulty, as it will permit dahabvehs to pass all the year round.