304 



THE POPULAR SCIENCE MONTHLY. 



First of all, tlie water-seal must be deep — never less than four 

 inches — and this seal must be exposed to view for reasons which 

 will be hereafter given. Again, there must be a considerable 

 depth of standing water in the bowl of the closet, to deodorize 

 fecal matter and to secure cleanliness. The outlet of the bowl 

 must also be completely submerged, to prevent its becoming foul 

 and offensive from use. The closet should invariably have some 

 device for maintaining the water-seal against loss from evapora- 

 tion. 



The traps of water-closets are especially exposed to the danger 

 of losing their seal. This happens frequently from the effect of 

 wind and other atmospheric disturbances. An open fire in an ad- 

 joining room, or a ventilator near by, may cause this loss of seal 

 from sudden draughts of air, and sewer-air frequently has free 

 entrance into houses for hours and even days at a time when the 

 danger is not suspected by the occu]3ants, since the water-seal of 

 the trap, in badly constructed fixtures, is wholly concealed from 

 view. 



In a series of careful experiments, conducted by the writer, it 

 was observed that even in well-ventilated soil-pipes, strong air- 

 currents prevail to such an extent as to cause the water-seal of 



traps to fluctuate with a 

 quick rise and fall, so that 

 enough water is soon spilled 

 over the outlet of traps to 

 unseal them entirely. The 

 results of these experiments 

 have recently been fully 

 confirmed by other investi- 

 gators. 



Of course, the more shal- 

 low the seal, the greater is 

 the danger of its being de- 

 stroyed from any cause ; 

 and for this reason a con- 

 t:, n u IV " w r^ „ slderable depth of water is 



Fig. 9—' Wash-out " Water-Closet, showing now "^^^ . . 



Accidental Obstructions may remain undetected reciuircd in the trap of eV- 

 iN TUB Trap which is concealed from View. , t j. tj. • 



ery water-closet, it is nec- 

 essary, also, that this seal should be plainly exposed to view, in 

 order that any loss of water from the causes just mentioned, or 

 by leakage, may be readily noticed. 



But it will be observed that the water-closets in most common 

 use have an extremely shallow seal. The reason of this is that, 

 with the imperfect means employed for flushing them, a greater 

 depth of water in the trap can not be allowed, since it would 

 seriously retard the outward flow of waste-water. The common 



