TANKS. The importance of collecting rain-water for domestic purposes, especially in districts where springs are deficient or lie at A great depth, has been much overlooked in this country. Mr. Waistell urges the im portance of placing spouts round all the buildings of a farm to collect the rain-water which falls upon them into a tank or tanks ; observing that, besides the value of the supply of water thus obtained, the buildings will be benefited by the walls and foundations being kept drier than when the water from the roof is suffered to fall upon them. He states that the quantity of water that falls annually upon every hundred superficial feet or square of building (in Great Britain) is about 1400 imperial gallons. therefore, the external surfaces of roofs were adapted to the collec tion of the rain water which falls upon them, and means were provided for conveying it to covered tanks, in which it might be preserved from evaporation, and kept free from any ad mixture of impurities, almost every house might be readily and cheaply supplied with a quantity of wholesome water sufficient for the ordinary wants of its inhabitants. The ex tensive roofs of churches and other public buildings might be employed in like way to collect water for the supply of ponds or tanks for public use. In some cases even the
drainage of lands might also be made avail able, as the water may be submitted to any required process of filtration before it is allowed to enter the tank.
Tanks or cisterns to hold water for domestic purposes may be conveniently situated be neath the surface of the ground, so that, being paved over, they occupy no valuable space. They are formed of stone slabs grooved into each other and set in cement ; of Welsh slate; of large paving•tiles bedded in cement; of brick-work; of plates of cast iron.; or of thick wooden planks, protected by charring and pitching, or lined with sheet lead. The brick tanks described byWaistell are circular, the sides being built like a well, with bottoms of an inverted dome-shape, of very slight con vexity. The top is also dome-shaped, and has an opening in the centre large enough to receive a man, in-order that the tank may be thoroughly cleaned out when necessary. This opening which maybe upon the surface of the ground, or a little above it, should be covered with an oak flap pierced with a number of holes, or with an iron grating.