68 



THE IRRIGATION AGE. 



between you and the company it is under no obliga- 

 tion in law or morals to furnish you any specific 

 quantity of water, or any at all, unless you can prove 

 a surplus above what is necessary to fill its contracts 

 with others. And by the time you have proved a 

 surplus the irrigating season may be over and you 

 will have to prove it over again for the next. 



WATER MEASUREMENT. 



Having secured through stock or contract a per- 

 petual right to a given quantity of water, how is it to 

 be measured out to you? 



The standard measure of water is the cubic foot a 

 second, or " second foot," as it is often called. If 

 you had a ditch a foot wide and a foot deep in 

 which the average velocity (not the top or center 

 velocity) was one foot a second it would give you a 

 cubic foot a second. If the velocity were two feet 

 a second it would give you two feet a second, and 

 so on. 



On account of the difficulty of getting the average 

 velocity, water in considerable quantities has to be 

 measured with a weir or the fall over a sharp-edged 

 board from a still pond. But this is inconvenient for 

 small quantities and it is not always convenient to 

 make a pond large enough to deaden the velocity of 

 the stream to a stillness reliable for accurate meas- 

 urement. The miners in early days therefore 

 adopted a pressure measure called the "miners' 

 inch " which now has become a legal measure in 

 some States and Territories. It is generally fixed at 

 a pressure of four inches and is the quantity that will 

 flow through a hole an inch square out of a box in 

 which the level of the water is four inches above the 

 center of the hole. 



As this will vary with the nature of the edges of 

 the hole, it becomes a purely theoretical measure de- 

 duced from the flow there should be from the laws of 

 gravity. A discount of about 36 per cent, is made 

 for the twisting of the water and other resistance to 

 its discharge, which leaves a flow of 13,000 gallons a 

 day, nine gallons a minute, or 540 gallons an hour. 

 These are in round numbers, which will be used all 

 through for convenience. They vary a trifle not 

 worth considering and only making them harder to 

 remember. 



This is a convenient measure because it is one- 

 fiftieth of a cubic foot a second. It amounts to 620,- 

 000 cubic feet a year, which equals 4,750,000 gallons. 

 This will cover an acre over 14 feet deep in a year, 

 and cover 10 acres about 18 inches deep. This would 

 give to 10 acres 6 irrigations of 3 inches each, which 

 would be much more effective than 6 rains of 3 

 inches each, as they generally come. From these 

 data you may figure out other things it will do, but 

 these are enough for all practical purposes. 



HOW TO USE THE WATKR TO ADVANTAGE. 



Suppose, now, you have an inch of water and ten 

 acres of land. You speedily discover that with an 

 inch flowing all the time you can do very little. It 

 keeps you constantly at work and limits you to the 

 use of basins so that you cannot wet the whole 

 ground. By the time you have the last of your tract 

 wet the first part needs water again, and you have 

 no time to cultivate properly. You are doing four 

 times the v/ork you should do and will get less than 

 half the results you should have. If you could let 

 that inch run into a reservoir for four or five weeks 

 or more and then let it all out in a few hours you 

 might wet something with very much less work. In 

 other words, you want not a continuous flow of one 

 inch, but so many 2^-hour inches at once. The equiv- 

 alent of a continuous flow for a year is what you 

 want, taken in quantities and for lengths of time to 

 suit your convenience. But when you come to figure 

 on a reservoir that will be tight, safe and not a nasty 

 mud-hole most of the year, you are staggered at its 

 cost. Anything like an artificial tank is very expen- 

 sive, and natural basins of any size with narrow 

 mouths, suitable for safe and cheap dams, do not 

 grow in every canyon. Your neighbors find the 

 same trouble. 



NO NECESSITY FOR A RESERVOIR. 



Well, why should you build a reservoir when the 

 ditch itself is one? Suppose there are 10,000 inches 

 of water in the ditch and 500 consumers want 20 

 inches each for 24 hours. With a little care on the 

 part of the management of the ditch they can all 

 have it. Suppose, farther, that there are 10,000 con- 

 sumers on the line, each with a 10-acre tract, with a 

 water right of an inch to 10 acres. They can all be 

 furnished 20 inches a piece for 24 hours in 20 days. 

 The expense and annoyance of 10,000 reservoirs are 

 thus saved. Some irrigators will want larger heads 

 of water for shorter times and others smaller heads 

 for longer runs. But they will average up so that 

 every 30 days one can have about what he wants. 

 The only restriction is that he cannot have it just 

 when he wants it. But if he sends in his order early 

 enough to give the ditch-tender or secretary time 

 to arrange his deliveries far enough ahead, he can 

 get his water at very nearly the time he wants it. If 

 disappointed this month, the company will try hard- 

 er to accommodate him to the minute the next time. 

 But after the first few times the irrigator will have 

 his crops accommodated to the times, so that 

 although not exactly what one would prefer, this 

 taking turns works very well in practice, and is the 

 only way of getting water in sufficient irrigating 

 heads without too much expense. 



