312 THE POPULAR SCIENCE MONTHLY. 



and cared for. Several phrases in this sentence will bear a little 

 amplification. 



In the first place, it must be clearly understood that the fixt- 

 ures and pipes which form an individual system of house-drain- 

 age are only a part of the apparatus required for the disposal of 

 offensive and dangerous refuse. Their external connections are 



an important part of this system, and, according to whether these 

 be with cess-pools or sewers, or whether these last are isolated or 

 are connected with many other houses, will depend the perfection 

 of the results obtained. In this article the house-drains and fixt- 

 ures only will be considered. 



Secondly, what is a " sufficient degree of safety " ? Absolute 

 safety can not be guaranteed by any system. If we can so 

 arrange the plumbing that, so far as it is concerned, the air in the 

 house shall be as pure and as free from specific causes of disease 

 as the air in the streets, it is the best that can be done. Reason- 

 able cost refers to that which is essential, and not to that which is 



