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which the pipe began. This pipe is made in the earthenware end of the tank itself. Thus it will be seen that a siphon is produced, so that when the tank is filled to the top, and the shorter limb of the siphon also filled up to the bend, a sufficient quantity of water thrown in suddenly will start the siphon, and so empty the tank of its contents to the level from which the lower limb starts inside the tank. The discharge end of the siphon has a weir placed across it with a notch in it. By means of these contrivances, not only will a smaller quantity of water start the siphon, but a false action, which was found occasionally to take place, and which caused the water to dribble away without the tank being emptied, is prevented. Thus the whole body of water contained in the tank is made to rush through the drains, and the difficulty spoken of above is avoided. The tank also acts as a very good fat trap. In towns, however, it is necessary to have sewers for the removal of the foul water.
Sewers ought to be impervious to water, so that their contents may not percolate into the soil around, and so drains which are made to dry the soil are obviously not fitted to be used as sewers. The larger sewers are usually made of bricks, and built with an oval section, this being preferable to the circular, and of course far better than any rectangular section. The bricks should be of the very hardest kind, and set in cement, and it is advisable to build the "invert,” or lower part of the sewer, upon invert blocks made of stoneware. For smaller sized sewers stoneware pipes are the best. They should always be used for sewers not greater than eighteen inches in diameter. Larger sewers than these are cheaper made with bricks set in cement. Stoneware pipe sewers would be much more used than they are in towns, but for the fact that the estimated size of the sewers generally is usually larger than is required, and much larger than would be required if the rain and surface water were carried away by separate drains. The pipe of the sewer only requires to be large enough to carry away the water that can be discharged into it, and anything beyond that size is an absolute disadvantage, as it makes it more difficult to flush the sewers properly, for a larger pipe is insufficiently flushed by a quantity of water that would easily flush a smaller one. For flushing purposes it is best to have an arrangement by which a considerable quantity of water is delivered into the sewer at once, so that it may fill it, or nearly so. The same quantity of water delivered more gradually does not produce by any means the same effect. In laying sewers, whether main or house sewers, provision should always be made for making new connections, without cutting into the pipes. This may be done by putting in junctions at various points—a plan especially suited for private estates, where the points at which junction may be wanted will suggest themselves. With street mains more ample provision should be made. Mr. Jenning's pipes, which allow
of the sewers being opened at any point without cutting the pipes, may be used. The pipes, in fact, have no sockets, the place of the sockets being supplied by divided rings, in one half of which the pipes are laid at their junctions, while the other half covers the upper part of the junction. With ordinary socket pipes, Messrs. Doulton's lidded pipes may be used with advantage. In these a third of the pipe cap be taken off along the whole length of the pipe, and so junctions can be made, the pipes inspected, and cleaning rods pushed down them when necessary. The “capped” pipes made by Messrs. Jones & Company, of Bournemouth, are also useful. They are constructed in the following way:-A semi-circular or semi-elliptical hole is cut out of each pipe at its end, so that when the pipes are socketed a circular or elliptical hole is left at the junction between the two. These holes are closed by means of lids made for the purpose, which may be removed at any time, for the purposes of inspection,