Waterworks upon an immense scale are in course of construction in various parts of West Australia. Among those recently completed are these at Mundaring, twenty-three miles from Perth, which are expected to have an important influence upon the gold mining in the Coolgardie and Kalgoorlie districts. The Helena river has been entirely dammed by a concrete weir rising too feet above the river bed, and having its foundations at one point 100 feet below the river bed. It is 700 feet long at the top, and fifteen feet wide there; eighty-five feet wide at the base; and provided with a waste weir and a free overflow five feet deep and 400 feet wide. The depth of water is too feet, and the river, which runs in a deep valley, feels the dam for seven and one-half miles of its course. The capacity from twenty feet above the river level, the lowest depth from which water will be pumped, is 4,600,000 gallons. But it is one thing to collect the water at Mundaring, 320 feet above the sea level, and another to force it through thirty inch pipes to Coolgardie. 1,400 feet ahove the sea level and 325 miles distant, and to Kalgoorlie. 1,230 feet above the sea level and twenty-five miles further off. This is done by eight sets of pumping stations, each with extra engines and pumps, in case of breakdowns, each set of engines being capable of pumping 2.800,000 gallons a day; and a number of minor and regulating reservoirs are provided, beside? service reservoirs at Coolgardie and Kalgoorlie.