CHAPTER XVIII. 

 PECULIARITIES OF BEHAVIOR OF WELLS. 



WELLS, although of almost infinite variety of type and con- 

 struction, are seldom distinguished by any marked departure, 

 either in characteristics or behavior, from the normal. Occasion- 

 ally, however, they exhibit peculiarities of a striking and puzzling 

 character. Among the most common of these anomalous phe- 

 nomena are the fluctuations of head, the variation in yield of 

 flowing wells with changes of weather, the roiliness of the waters 

 during storms, the blowing, sucking and breathing of wells, and 

 the freezing of the wells at points far below the surface. 



Fluctuations of Head. --The ordinary variations of head, or 

 the level to which the water rises in a well, depend on perfectly 

 simple and well-known factors, such as variation in rainfall, melt- 

 ing of snow upon the surface, thawing of frozen ground, etc., all 

 of which affect the supply of water penetrating the soil and reach- 

 ing the wells. There is, however, another class of fluctuations of 

 less frequent occurrence and of more obscure origin. In such 

 fluctuations the water level rises and falls periodically, commonly 

 standing lowest at about 10 A.M. and 9 P.M. and highest at about 

 3 A.M. and 4 P.M., but fluctuating much more widely during the 

 passage of storms, the water rising on their approach and sub- 

 siding as they pass away. The daily variations are commonly 

 under an inch, but the fluctuations marking the progress of storms 

 often amount to several inches. Some wells that must be pumped 

 during fair weather flow freely during storms. 



Variations in Yield. Where the head of the water in a tubular 

 well is just sufficient to bring it to the top, the well is often very 

 sensitive to changes of weather. A few wells flow at fixed hours, 

 as at about 3 o'clock in the morning or at approximately 4 o'clock 



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