VERTICAL DRAINS 



125 



sinkhole, or a cavern in the underground rock, affords a splendid 

 outlet for a system of tile drainage. 



Fig. 60. — Can any good thing come out of this marsh full of brush, cat-tails, reeds, and 



rushes? (See Fig. 61.) 



Fig. ei.^Corn that will fill the silo to good measure has been grown on the same marsh 

 as shown in Figure 60, after being properly drained. 



Now and then a drilled well, or one dug and filled with stones, 

 furnishes the only possible means whereby water in basins can be 

 drained out. Not all wells made for such a purpose prove success- 

 ful—this one may fill with water, while another may bring to 



