An attempt has been made to improve it by having a stoneware container, with a place for ventilation at the side, only it is an attempt to improve a radically bad arrangement, and not worth further consideration. Underneath this closet apparatus you will, as a rule, find, if you take the woodwork down, a tray of lead, called the “safe” tray. But there is no other word in the language that would not be a better description of it than this word! This tray is intended to catch any water that may escape from leaky pipes, or any slops that may be thrown over; and so it is necessary that this tray should have a waste pipe. The waste pipe in nine out of ten cases, probably in much greater proportion, goes into the trap immediately underneath the closet, and so it forms a communication for foul air from this trap to get into the house.
In some instances it goes directly into the soil pipe, and forms a means of ventilation of the soil pipe into the house. Sometimes a trap is put on this waste pipe, and it is then connected with the soil pipe, which goes on well so long as there is any water in the trap; but as soon as the water becomes evaporated, foul air gets into the house again.
Sometimes (to show the ingenuity which people often expend upon bad things) this waste pipe has a trap, and a little pipe from the water supply fixed to feed the trap; but all these ingenious plans have been devised in order to improve upon a principle radically wrong. The pipe should be carried through the wall and end outside the house as a warning pipe.
Scarcely any water ever comes out at all; if any does come out, it shows there is something wrong, so that this pipe should pass through the wall, and be made to discharge outside the house.
In order to prevent wind blowing up the pipe, it is usual to put a small brass flapper on the end. Its weight keeps it shut, and the pressure of water opens it.
Underneath the safe-tray you will find as a rule a trap of some kind, and generally the trap that is found is a D trap, a trap whose name indicates its shape, and which cannot be washed out by the water that passes through it. The pipe from the closet passes so far in it that it dips below the level of the out-going pipe, and thus forms a sort of dip-trap. The pipe which is the inlet from the closet is not placed close to the edge, but a little way in, to form a receptacle for all kinds of filth!