214 Introduction to the Study of Science 



are easily provided in several simple and more or less perma- 

 nent ways. 



The old-time cesspool and the modern septic tank made of 

 cement are two familiar devices which are widely used in pro- 

 viding the conditions in which putrefying bacteria thrive and 

 work. In the use of the septic tank there are none of the dan- 

 gers to health which attend a carelessly kept cesspool. 



Both of these devices require a sufficient water supply. 

 This should be available in every rural home, together wi h 

 the conveniences which such a supply makes possible in the 

 kitchen, bathroom, laundry, and garden. There are several 

 comparatively inexpensive and easily cared for systems which 

 give such a supply. A tank placed in the attic, or elevated 

 outdoors, or a tank in the cellar where pressure is supplied 

 by a compression air-pump may meet this need. The tank 

 may be kept full from an upland reservoir, from a well pumped 

 by a gasoline pump or windmill, or from a stream by the aid 

 of a hydraulic ram. All of these are familiar in rural life. 



The cesspool. With an adequate water supply the sewage 

 problem may be settled for a time by the cesspool, the cheaper 

 and more easily constructed of the two devices named. This 

 is merely a hole in the ground, about ten feet deep and three 

 or four feet in diameter, lined with uncemented stones, and care- 

 fully covered with heavy planks. It should be fifty or more 

 feet from the house. The drainage from it should be away 

 from the water supply. The cesspool requires care, regular 

 cleaning, and at intervals a strong lye solution must be added to 

 dissolve the heavy greasy scum that collects upon the surface 

 and the stone lining. Such treatment does not favor the 

 beneficial bacteria to any great extent, but some manage to 

 thrive and bring about desirable changes in the contents. 



The septic tank. The septic tank, which was first tried out 

 at Exeter, England, in 1893, has much more to commend it 

 than the cesspool. It is made of concrete and provides per- 

 manently the conditions which favor rapid and complete putre- 



