THE UllilGATlOS AGE 339 



straight. Having determined on the location of the reservoir, the next 

 question to be determined is, what is the present grade of the local ion ''. 

 If it is found that the grade is about right, then you are ready to de- 

 cide on the shape and size of the reservoir; but if the reservoir site is 

 found to be much higher than desired, calculations should be made 

 to drop the bottom of the reservoir lower than the usual one foot: 

 and if the site is lower than it should be, soil that is of a gumbo na- 

 ture should be hauled in to raise it. and calculations made to take all 

 the dirt for the banks from the outside. 



SHAPE AND SIZE OF RESERVOIR. 



The reservoir that will give the greatest storage capacity for the 

 amount of embankment required is the circular, and for a small^ res- 

 ervoir it is much more desirable than the rectangular. If it is thought 

 best to have a large one, it should be made oblong without being rec- 

 tangular. The corners not only cause more work in the construction, 

 but the shaps of the ressrvoir is objectionable, for the reason that the 

 waves in such a reservoir have greater force. Irrigation with pumpad 

 water so far in this state has been principally confined to small opera- 

 tions: and on account of the evaporation being so much greater from 

 a larga surf ACS thin from a small oas, aril as th? S33piga, little or 

 much, will increase with the dimensions, small reservoirs are usually 

 preferred. A shallow reservoir, on account of the increased tempera- 

 ture of the water, will lose much more through evaporation. It is 

 also claimed that warming the ground increases the seepage, and as 

 warming the water, would to some extent warm the ground, the tend- 

 ency of the shallow reservoir would be towards increasing the seep- 

 age, though it may be that the difference in the pressure would make 

 up for the increased temperature. There will be very little seepage if 

 the reservoir is properly constructed. Circular reservoirs form 30 to 

 60 feet across, and holding about six feet of water, would be good di- 

 mensions for ordinary use, and 60 by 80 or 100 feet would be good 

 proportions for a larger one. The longer way should extend east and 

 west on account of the prevailing winds. Of course, the deeper the 

 water the less it will be affected by the wind. 



BUILDING A RESERVOIR. 



The first step, after removing any rubbish that may be in the way, 

 is to lay off the ground large enough for the reservoir and one-half 

 the banks. It has been found very difficult to prevent the seepage of 

 water where the banks and bottom come together, and it is much 

 better to make sure of it while there is a chance. If the grade will 

 allow, it is better not to remove more than one foot of the top soil, 

 except where it is found necessary to make the bottom level. Ten 

 feet of the ground under the bank will require puddling with the 



