THE IRRIGATION AGE. 109 



and materials for underground drainage, and therefore need not be 

 further discussed in this connection. 



There is, however, one matter in connection with a projected util- 

 ization of a spring or any small outcropping of water to which careful 

 attention should be given, and that is approximate knowledge of the 

 amount of water which can be made available. This may be obtained 

 before investment of labor or material is made, by opening up the 

 spring thoroughly, cleaning it out to expose its outflow, and measur- 

 ing the flow in a water-tight basin or a vessel of known capacity. Note 

 the time required to fill the vessel and it can be quickly calculated how 

 much the spring will yield in twenty-four hours. Almost every one 

 will be surprised at the result of the measurement;; a trickle of water 

 thought to be too insignificant for consideration will be found to yield 

 a very effective continuous flow if the water is collected. A five-gallon 

 oil can is a handy measere. Suppose the spring fills it in two min- 

 utes, the yield would then be 3,600 gallons in twenty-four hours, or 

 108,000 gallons in one month, and this amount is equivalent to nearly 

 four inches of rainfall on an acre of ground. Such an amount, if care- 

 fully collected and applied, would keep a garden of small fruits and 

 vegetables in good growth, even with very little rainfall, if the soil 

 be of fairly retentive character; as a safety supply against the short 

 drouths of the humid region it would rescue a crop which might be 

 worth several hundred dollars. 



Thus a little outflow from a spring, which might pass away unno- 

 ticed unuerground, or at most by surface flow would only make a 

 sedgy streak across a corner of a field, can be made a potent foctor in 

 production. Of course, in handling water from such a small source 

 of supply, it must be constantly protected from loss. It would disap- 

 pear in an open ditch in a short time. Usually it must be conveyed in 

 a pipe to a tank or tight reservoir and collected in sufficient volume to 

 cover quite an area at each application. 



COLLECTION OF WATER FROM SIDES OF CANYONS AND RAVINES. 



In the same class with development of springs is the collection of 

 water from banks in canons or ravines where floods have uncovered 

 water-bearing strata. Water seeps out on these surfaces and sinks 

 away in the debris which is usually found in such places, reaching at 

 length the stream bed and passing away as surface flow or underflow, 

 according to the character of the stream bed. Sometimes, where the 

 difficulty of making the submerged dam is too great, the outcropping 

 from the bank alone may yield as much as a good spring and be se- 

 cured by cutting out a ditch at the bottom of the bank, cementing it 

 or clay bedding it well, or bedding in a plank box and connecting by 

 a pipe with a reservoir, in the came way as in case of a spring. 



To be continued. * 



