36 ENGINEERING FOR LAND DRAINAGE. 



the soil. In others it is only partly accomplished, the 

 remainder of the work to be done by the enterprise of 

 man. 



He who drains land for any purpose whatever should 

 put it down as a first principle that he is only aiding 

 Nature, and hence he must work in accordance with 

 her laws. We frequently take too much credit to 

 ourselves in thinking that we have invented some 

 new method, when we have only developed the plans 

 as they have been pointed out to us by Nature. A 

 very little artificial work in addition to natural ad- 

 vantage will sometimes bring about complete drainage, 

 while in other cases great labor and expense will be 

 necessary to accomplish results no more complete. 



The first question to be asked where agricultural 

 drainage is contemplated is, will the land be productive 

 after drainage? If this question, after proper investi- 

 gation, must be answered negatively, the matter should 

 be dropped, if the agricultural value of the land is the 

 only one to be considered. Some wet lands have no 

 productive value before drainage, nor will they after- 

 wards, though it may be said for our encouragement 

 that such cases are exceptional. 



The second question is, can the land be drained, and 

 if so, how, and at what cost? It will be the writer's 

 object to deal with this question in its practical details, 

 under appropriate divisions of the subject. 



Underdrainage. 



No soil is completely drained of its surplus water, 

 unless it is done by the process known as underdrain- 



