FURROW IRRIGATION. 69 



sent the required grade for your ditch. In this way the 

 work can be done very rapidly. 



"The same thing is equally good for laying common 

 little flumes, cement ditches, etc. But in earth, one should 

 determine by trial the amount of slope the soil will stand 

 without cutting or filling up with sediment or refusing 

 to run fast enough in case the soil is very porous. A 

 mistake of a few inches in a hundred feet will generally 

 not be serious, but the more nearly exact you can get it 

 the better. Every approach to perfection in your first 

 arrangements diminishes your future work and annoy- 

 ance. 



"All manner of stuff is now raised in this way in Cali- 

 fornia on hillsides that a few years ago, when covered 

 with brush, seemed too steep and rough even to plow. 

 When once made, the furrows, of course, are left in place, 

 but the water finds its way to the center between them 

 quite as well as on more level ground." 



Irrigation by Sprinkling. Systems of iron pipe laid 

 below reach of plow and spade and furnished with stand 

 pipes and revolving sprinklers, or other showering de- 

 vices, have been successfully used to a limited extent, 

 and some have strongly favored them in spite of the con- 

 siderable cost of the outfit. They are worthy of consid- 

 eration where water under adequate pressure is avail- 

 able. They are labor-saving, but they encourage neglect 

 of cultivation, and to that extent are undesirable, espe- 

 cially on soils which harden on drying. 



Sub-irrigation by Tile or Pipes. Californians have been 

 experimenting with subterranean distribution with tile 

 or specially constructed pipes and outlets for probably 

 more than forty years, and yet none of the proposed sys- 

 tems has ever come into use except under the eye of the 

 inventor. In early days, iron troughs inverted on red- 

 wood boards; small flumes or boxes of redwood boards; 

 bricks set on edge and covered with boards; drain tile 

 with and without perforations all these were suggested, 



