2IO 



MICROBIOLOGY OF WATER AND SEWAGE. 



the drainage. Water falling on the surface of the ground would pene- 

 trate through the soil to the upper portion of the subsoil, and then move 

 along it in the direction of the greatest slope. In this sketch, the subsoil 

 drainage is away from the well; and in this respect the well is located 

 properly; but, in respect to the surface drainage, improperly located. A 

 better place for the well would be at the letter "X." 



In Fig. 6 1 the surface drainage including that from the adja- 

 cent outhouse at 3, which is too close to the well is toward the barn, 

 and away from the well; but the subsoil drainage from all the buildings, 



FIG. 63. Construction of a model well. On the right is brick construction, on the left 

 stone construction, as illustrated. (Original.) 



except the house, is in the direction of the well; and thus contamination 

 of the water supply is liable to occur. 



Fig. 62 shows a well properly located as regards both surface and 

 subsoil drainage. Such a well will supply pure water, if it is properly 

 constructed. 



Figure 63 shows the proper construction of a well with brick or stone. 

 Large vitrified drain pipes with cemented joints will answer equally well 

 when there is an abundant supply of water; but in case the supply of water 

 is limited, a large area is needed, and a stone or brick well is necessary. 



