LAND DRAINAGE PRACTICE. 49 



While the above refers particularly to hillsides re- 

 quiring drainage, it is also applicable to flat land hav- 

 ing any slope whatever. There are sags, swales, and 

 ponds into which an outlet tile must be extended by 

 the most feasible course; after that the general rule 

 applies. 



Avoid short laterals where a system can be adopted 

 in which long parallel laterals can be used. This 

 is a matter that has to do with the economy of the 

 work rather than with its efficiency. Every main or 

 sub-main will, of itself, drain the land for a certain 

 distance on either side of it. All laterals, in order to 

 reach these mains, must be laid through the belt of land 

 thus drained, and hence a part of each lateral will be 

 useless except to conduct the water to its receiving 

 drain. The fewer junctions there are in a given tract 

 the less waste of length of lateral drains will be there. 

 There are localities where, on account of the contour 

 of land, the short laterals are necessary. 



Make the lines as straight as practicable, and 

 change direction by easy curves. Drains cannot 

 always be made straight from one end to the other, 

 yet short serpentine crooks should always be avoided. 

 Tangents may be run and connected by good curves 

 which will admit of the drain being put in the proper 

 place and accomplish the work far better than can be 

 done by irreefular crooked lines which usually mark the 

 ™.ll L„L„a. The disadvantage, of a crooked 

 line are that the tiles are laid with greater difficulty and 

 more imperfectly, there is a loss of grade where it is 

 needed, the friction of the running stream against the 

 walls of the drain is greater than in straight lines, and 



