168 ELEMENTS OF GENERAL SCIENCE 



180. Sewage disposal. Much of the waste is in solid form 

 (garbage, ashes, etc.), and the proper disposal of this is im- 

 portant and difficult. We shall here concern ourselves only 

 with that which is washed away in running water the 

 sewage. That there will be a great volume of this is evident, 

 for most of the water that is pumped into the city eventually 

 finds its way into the sewers. In addition most of the water 

 from rains is turned into the sewers by the catch basins in 

 the gutters. 



The simplest way to get rid of waste water and sewage 

 is to allow it to run off over the surface of the ground in 

 gutters. This objectionable practice is common in oriental 

 cities, and even some American cities still permit such a 

 system. Indeed, open sewers may be found in neglected parts 

 of many of our cities. An open sewer is always a source of 

 danger and should be a matter of concern to every citizen. 



The modern and sanitary way to construct sewers is to 

 place them underground. There is usually a sewer in every 

 street, and every house should be connected with it. The 

 smaller sewers unite with larger ones, which finally discharge 

 the sewage into a lake, river, or ocean, or, what is far better, 

 into a modern sewage-reducing plant. 



181. A sanitary canal. Although Chicago is in the basin 

 of the St. Lawrence River, at the present time its sewage 

 flows into the Gulf of Mexico. The way this was accom- 

 plished forms an interesting illustration of what a modern 

 city will do to dispose of its sewage so as not to spoil its 

 water supply. The route which afforded an easy passage for 

 the Indians, the French (Chapter XIII), and the builders of 

 the Illinois and Michigan Canal and of wagon roads and rail- 

 roads has proved equally suitable for the route of the canal 

 built to carry away the sewage of Chicago. 



The building of this canal was possible because, as stated 

 in the preceding chapter, no part of the old portage was more 

 than fifteen feet above the level of the water of the lake. The 



