SANITARY DRAINAGE OF WASHINGTON. 9 



true that a deleterious condition of the contained air of the soil is 

 due to the character of the decomposition within that soil of the 

 organic matter which may have been added to it by vegetation, or 

 which may have reached it from the ofT-scourings of human life. 

 We know that the oxygen of the atmosphere is the great scavenger 

 on which we must depend to destroy these injurious matters in the 

 ground ; we know that its penetration into the soil is impossible 

 when this is filled with water, and that its entrance is more and 

 more free, and its action more and more effective, in proportion 

 as the interior spaces of the earth are rapidly emptied of the water 

 which they may receive from rains. We know, too, that the down- 

 Avard movement of water through the soil carries with it to the 

 drainage outlets below, whether natural or artificial, the oxidized 

 products of decomposition, and that as the water descends the 

 spaces which it had occupied are filled with fresh volumes of air. 

 We know, too, that the good effects which attend such descent of 

 water in the soil, are substituted for the bad effects of a rising 

 from below of the water of saturation, which fills the pores of the 

 earth, and prevents or impedes the necessary work of atmospheric 

 destruction. 



There are parts of your city, some low-lying and some high- 

 lying, which have so little inclination of the surface that rain- 

 water does not readily flow away, but remains to soak slowly into 

 the ground, which is of so nearly an impervious texture that the 

 underground escape is extremely sIoav, if it is not practically ab- 

 sent. In many districts much of the water by which the earth is 

 wetted, lies clogging its pores, until removed by a chilling evap- 

 oration, accompanied by the escape of unwholesome gases from the 

 unclean earth. 



So far as this defective drainage exists in Washington, and it is 

 by no means exceptional, the best or even tolerably good sanitary 

 surroundings cannot be hoped for. In so far as the atmosphere of 

 the city is insalubrious, it is not to be doubted that its insalubrity 

 is directly or indirectly due more largely to the saturated condition 



