PECULIARITIES OF BEHAVIOR OF WELLS 



139 



oxide may be precipitated in the earth from chalybeate waters, 

 although it may not ordinarily be present in amounts large 

 enough to be noticeable in the water drawn from a well, but dur- 

 ing periods of low barometer this oxide is disturbed in much the 

 same way as is the silt, and mixes with the water as a yellow or 

 red precipitate, rendering it unfit for use. 



In wells that do not flow occasional turbidity is more difficult 

 to explain, but the motion of the ground water tapped by these 



FIG. 61. Supposed conditions producing discoloration of waters in non-flowing wells. 

 A, normal water level in bed; a, normal water level in well; B, level in water bed 

 during low barometer; b, level in well during low barometer. Arrows indicate 

 direction of ground-water movement due to changes in barometric pressure result- 

 ing in disturbance of fine particles of clay or iron. 



wells is no doubt caused by changes in barometric pressure and, 

 as the phenomena occur under identically the same conditions, it 

 is probable that they are due to the same general cause. 



Remedies for Freezing Wells. Several simple methods of 

 preventing wells from freezing are in common use, but, owing to a 

 failure to understand fully the causes of the freezing, many of 

 these methods fail and others are only partly successful. Some 

 persons have the idea that freezing is caused by the chilling of the 

 air inside the well by the transmission of the cold outside air 

 through the casing, to remedy which the pumps are carefully 

 wrapped in cloth, packed with straw, or otherwise protected. 

 As a rule, this protection is entirely without effect, for the freez- 

 ing does not occur in the manner assumed, but by access of air to 

 the pipe at considerable depths. Other persons partly recognize 

 the true cause of freezing and make an attempt to prevent access 

 of air by packing earth, straw or other material about the well. 

 This practice is partly successful, as it tends to check the indraft 



