SPRINKLING AND SUB-IRRIGATION 55 



sometimes the flume is laid in steps connected with a bit of covered flume 

 from step to step. The latter is best for very steep hills, though, with care, 

 the other may be used on a greater slope than one would imagine. Another 

 flume should be laid at the end of the furrows to carry off the waste water. 



The contours may be laid out by anyone with a carpenter's common 

 level. Fifty-five feet to the mile is nearly right for a very fine stream on 

 most soils. And this is about one foot in ninety-six, or two inches in sixteen 

 feet. Therefore take a sixteen-foot plank and level it to a slope of two 

 inches in its whole length. Then when the upper edge of this is level the 

 lower edge will represent 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 arrange- 

 ments diminishes your future work and annoyance. 



All manner of stuff is now raised in this way in California 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 revolv- 

 ing sprinklers, or other showering devices, have been successfully 

 used to a limited extent, and some have strongly favored them in 

 spite of the considerable cost of the outfit. They are worthy of 

 consideration where water under adequate pressure is avialable. 

 They are labor-saving, but they encourage neglect of cultivation, 

 and to that extent are undesirable, especially on soils which harden 

 on drying. But surface crusting is obviated by using a very fine 

 spray and on some soils is not likely to occur even with coarse 

 sprinkling. 



Sub-irrigation by Tile or Pipes. Californians have been ex- 

 perimenting with subterranean distribution with tile or specially 

 constructed pipes and outlets for probably more than forty years 

 and yet none of the proposed systems have ever come into use ex- 

 cept under the eye of the inventor. In early days iron troughs 

 inverted on redwood boards; small flumes or boxes of redwood 

 boards ; brick set on edge and covered with boards ; drain tile with 

 and without perforations all these were suggested, given trial and 

 abandoned. All experiments proceeded upon the plan of thus 

 making permanent water conduits below the point reached in spad- 

 ing or plowing, and they all became inoperative. The failure was 

 usually charged to the filling of the pipes with plant roots and in 

 some cases this was seen to be the reason. In other cases the failure 

 of the system was due to the fact that in light soils lacking capil- 

 larity, the water rapidly sank away from the pipes out of the reach 

 of the roots and shallow rooting plants failed though there was 

 moisture flowing to waste through a pervious subsoil. Mr. E. M. 

 Hamilton of East Los Angeles invented a system of continuous 



