DOMESTIC WATER SUPPLIES FOR THE FARM 



well-point type of screen have already been described in the 

 chapter on driven wells. Other screens, the use of which is not 

 limited to driven wells, are described below. 



One of the most common forms of 

 screen consists of an ordinary iron pipe 

 perforated with quarter-inch holes placed 

 about 2 inches apart, the whole being 

 wound with iron wire. The closeness of 

 the winding is dependent upon the fineness 



FIG. 50. Well strainers: a, Layne strainer; b, Cook strainer. 



of the material in which the water is found. Some of the screens 

 of this type are as much as a hundred feet long. 



Many waters, such as those of considerable areas of the lower 

 Mississippi valley, rapidly attack all forms of iron or galvanized 



