DUTY AND MEASUREMENT OF WATER. 1 45 



water divided into four canals flowing a mile an hour 

 will run two and a half miles in the same time if car- 

 ried through one canal. The seepage of a full head of 

 water distributed through four canals is three and a 

 half times as much as when held in one body. The 

 evaporation is six times as much when divided 

 into four parts as when held in one body. This 

 comes from the fa(5l that a small stream becomes much 

 more heated than a large one. The small one runs 

 slowly, while a heavy body flows fast. Then there 

 are four surfaces instead of one exposed to sun and 

 wind. The waste of water running through four 

 canals or ditches is very great. If a fifty-inch flow of 

 water will cover one-quarter of an acre an hour 100 

 inches will cover three-quarters of an acre in an hour, 

 200 inches two acres in an hour, and 400 inches five 

 acres in an hour. The difference in irrigating five 

 acres an hour and irrigating one-quarter of an acre in 

 an hour is that the former requires two strong men 

 while in the latter case a boy only is needed. A full 

 head will irrigate evenly, but a small stream will soak 

 the upper end, while the lower end is yet dry. Some 

 writers have thought to remedy this matter by giving 

 each canal its water in bulk by the hour instead of a 

 small constant flow. The canal running full capacity 

 so many hours a given length of time would thus 

 give each user a full head for all the hours of his time. 

 Furthermore, a man when he knows he is going to get 

 a good head of water in time of scarcity will clean out 

 his ditches and be fully prepared for the water when 

 it comes. To do this, however, in most of the west- 

 ern states would require the substitution of new laws 



