THE IRRIGATION AGE. 231 



it for the whole distance it would then carry more than one inch. 

 But its capacity is now reduced to one inch by the resistance and that 

 resistance necessarily holds the water up to the top of the flume. 



You cannot avoid this conclusion except by jumping the terms 

 of your own proposition. The consequence is that you cannot in this 

 way reach the source and therefore 



CANNOT LOWER ALL THE WATER PLANE AS LONG AS THE 

 SUPPLY LASTS. 



The hydraulic curve formed by the lessening of the resistance at 

 the end will vary with the character of the material, but in no case 

 can it run back very far. In the Yarwood case we bored some fifty 

 wells to test the theory, connected them all by the level and plotted 

 the results. The curve ran out entirely in three hundred feet or over 

 nine hundred feet below the land of the plaintiffs, showing that the 

 lowering of the wells must have been due to failure of the supply far 

 above. This was farther shown by the fact that the area over which 

 the lowering occurred would have doubled the flow in the cut for 

 several weeks had it all gone out that way. But there was no 

 increase in the flow over that which continued for many months 

 thereafter and the plaintiffs, though living where they could readily 

 see and measure any such increase, did not attempt to show any. 

 The sheet of water in this case rose again three hundred feet below 

 the cut and moved on as if nothing had happened, the supply 

 evidently coming up from below at that point. 



The consequence is that several wells may be bored into such 

 a stream not under pressure, and if not too close, so that one comes 

 within the cone of depression formed by the other, each may get its 

 share of the water without damage to the supply which would pass 

 away to the sea if not thus taken. But if under pressure the same 

 number of taps would probably increase the flow between the upper 

 well and the mountains so as to let out the supply much faster. 

 Thus a stream not under pressure may be a safer supply than one 

 under pressure though it may cost more to raise the water. 



Every kind of tunnel and opening out of a spring is only drawing 

 on a reservoir. Anything more than absolutely necessary is danger- 

 ous waste. It is simply opening the gate too wide and leaving it 

 open. In small ware sheds such development is apt to 



FAIL ABOUT THE TIME YOU NEED IT MOST. 



If you can dam up the tunnel and have it run only when needed 

 do so. The same with a cut in a cienaga. I have known several 

 springs completely lost by splitting the bed rock in blasting, and 

 others that were permanent before opening have been opened so 

 much that they have become dry before summer was half over. In 

 all cases where it is evident the water comes from a local watershed 

 calculate the amount that one-half the rainfall, falling on the area 



