OTHER CONDITIONS AND PROBLEMS 153 





is turned into it. The top stones should be small, and 

 upon these should be placed gravel, then sand, then the 

 regular soil of the field. The writer has in mind one such 

 arrangement in which a tile system, draining something 

 like 160 acres, discharges its water and has been in success- 

 ful operation for many years. In depressions of limited 

 area, such a well at the lowest point and with the stone 

 coming to the top is 

 frequently sufficient to 

 carry away the excess 

 of water without the 

 aid of tile. (See Figs. 

 64 and 65.) 



203. Drain heads. 

 Instead of construct- 

 ing a well, as above 

 described, the practice 

 is becoming somewhat 

 general of installing a 

 vertical system of tile. 

 Six-inch tile are usually 

 used, and upon these 

 is sometimes set what 

 is known as a drain 

 head, a device rather 



commonly advertised in agricultural papers. When the 

 vertical tile system is used, the horizontal drains are 

 dispensed with. Instead, a number of vertical systems 

 are introduced, if one is not sufficient to drain the whole 

 area. 



204. Drainage by wells. Vertical drainage, probably 

 beginning in formations of drift origin, has been extended 

 to soils overlying other than drift deposits. 



FIG. 64. The way of constructing well 

 for drainage downward into under- 

 lying gravel. 



