CHAPTER XII. 



BORED AND PUNCHED WELLS. 



Advantages and Disadvantages. Bored wells, which include 

 those sunk with various forms of earth augers, and punched wells, 

 sunk by dropping slit steel cylinders, together constitute a type 

 intermediate between the dug well and the driven and drilled 

 wells (Fig. 35). The larger of the bored wells are closely related 

 to the dug wells, inasmuch as they are commonly fitted with per- 

 vious curbs, and many of them differ only in size and method of 

 removing the earth. The smaller bored wells, and most of the 

 punched wells, on the other hand, are provided with tight cas- 

 ings, and are more nearly related to wells of the driven or drilled 

 types. 



A summary of the good and bad features of bored and punched 

 wells is given below. 



Bored wells (Arkansas type, 2 to 12 inches in diameter, light casings). 



Punched wells. 



When provided with pervious curbings the ad- 

 vantages are similar to those of open and Iowa 

 type bored wells; when provided with tight 

 casings the advantages are similar to those of 

 the Arkansas type bored wells. 



Similar to those of open wells and the larger type of bored 



wells. 



Difficulty of operation; liability of crooked holes. 

 Usual limitation to depths under so feet. 

 Limitation to soft yet stiff materials, which are generally 



of local distribution. 



