An Immense Reservoir.
The Bhatgur reservoir is a great artificial lake in India holding about 4,641,000,000 cubic feet of water, and acting as a feeder to the Nira canal, one of those long irrigating water courses used for navigation on its lower portion. This reservoir is formed by a masonry dam 103 feet high and 3020 feet long, which is noteworthy even in a country of great dams. In order to hold as much of the valuable water as possible, a portion of the top of the dam about 810 feet in length is provided with a series of gates which are raised until the water reaches the highest level for which the reservoir was designed, and then are automatically lowered until the surplus water has escaped. Each gate is ten feet wide and eight feet high, and runs up and down in a vertical frame. To its top is attached a chain which runs over a pair of pulley wheels to a cylindrical counterweight, moving up and down in a water-tight compartment. As soon as the water begins to flow over the top of the dam, the chamber is filled, and the counter-weight, being surrounded by water, is no longer heavy enough to keep the gate raised, so it falls. As soon as the flood is over, the chamber drains, the counter-weight sinks to the bottom again, and the gates are raised so as to hold back all the water entering the reservoir. These gates are said to be working satisfactorily.