UNDER the heading "Thorough Flushing," we must reject all plumbing fixtures and their traps whose outlets are smaller in their clear water-way than their waste-pipes. Under this head will fall nearly every form of wash-basin known, and many forms of traps.

The common plug and chain basin (Fig. 15) illustrates most forcibly the very defective construction referred to. The entire value of the pipe-scouring power of the waste water is thrown away, and the result is a gradual accumulation of filth throughout the whole waste-pipe system.

Fig. 15. - Ordinary Plug and Chain Basin.

The advocates of trap venting point to this dangerous accumulation as an argument in their favor, ignoring the fact that there is absolutely no reason whatever for its existence.

Finding one unsanitary condition of things, instead of studying the cause, they immediately add another and still more unsanitary condition, which brings into play all the dangers of the first, instead of removing them. The trap vent-pipe evaporates out the water seals of the traps and permits the foul gases of organic decomposition to enter freely into the house, when without the vent-pipe, they would have been carried off into the soil-pipe by the natural action of the water.