226 



FARM DEVELOPMENT 



upper end, if sufficient fall can be provided so that 

 the water will run with rapidity and make the ditch 

 clean itself of silt and not become clogged. The distinc- 



Figure 127. Narrow deep ditch with braced poles protecting 

 the sides from washing. 



tion between a sewer and an underdrain may be stated 

 as follows : The sewer receives surface water contain- 

 ing solid materials, while the underdrain, the upper end 

 of which is usually closed by a stone or broken piece of 





Figure 123. A. drainage well beside 

 ing water from the pond into the well. 



a pond. B, tile drains conduct- 



