A MAMMOTH DAM.

Towards the end of 190-2 the danger of a shortened allowance of water set the people of Sydney, Australia, on a keen lookout for a further source of supply. The city and suburbs were fed from the Prospect Dam, a huge sheet of water, which, till the worst period of the worst drought that the country had ever known, sufficed for all demands. A restricted supply of water was a situation which the average citizen could not endure, wherefore, they joyed when the government decided on the construction of a reservoir of much superior capacity to the one in use. A favorable site was immediately selected, and operations in connection with the clearing of the land, the excavation of the earth, and the building of the embankments were initiated without delay. Since then the work of construction has proceeded without pause, and, when the dam is completed, it will be the most capacious of its kind in the world. The main wall will have a length of 1,000 feet, a width at the base of 100 feet, tapering to twenty feet at the top, and will be 160 feet in height. Its capacity, when full, will be 23,000,000.000 gallons, or twice as much water as that which the present supply dam is capable of holding.

The Cohoes, N. Y. people are anxious to have wholesome water, and will install a filtering plant of about 8,000,000 gallons capacity—the amount needed in winter: A supply was hoped for from the Shaker settlement, where the water is very pure, but only 3,000,000 gallons can he furnished daily. Near Schenectady a source of water supply, the Applaus Kill, could be obtained, the water to flow to No. 3 reservoir by gravity. That plan, however, would have cost $500,000.