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Transactions of the 



is obliged to hire laborers. It is plain on the slightest consideration, 

 that the cost of a canal will be so dependent on local and special cir- 

 cumstances, that it is impossible to deduce a perfectly satisfactory con- 

 clusion from a given or h} T pothetical case. 



The dam, the character of the soil, the quantity of land to be irri- 

 gated; the manner in which it is disposed; the relative remoteness, and 

 the resources and population along the line, arc all elements which vary 

 from case to case, and cither of which may affect the cost by a very 

 considerable percentage. 



PROBABLE COST OP CANALS. 



Still, it seems essential to know within some limits the probable cost. 



If a canal is to cost one hundred dollars per acre irrigated, the subject 

 may be dismissed without any further consideration. It is plain that we 

 cannot afford to pay that price. If, on the other hand, canals may be built 

 for five or twice five dollars per acre, it is equally plain that now, or before 

 many } r ears, we shall be able to afford them, and shall have a fair pros- 

 pect of return from such investment. The value of the estimate which 

 we proceed to give will be understood from w r hat precedes. Let us take 

 the most favorable case that can happen, namely, when the excavation 

 equals the embankment. We assume a canal to carry three hundred and 

 fifteen cubic feet of water per second, having the dimensions given in 

 the figures: 



WHAT ONE MILE OF CANAL WILL IRRIGATE. 



Deducting from this fifteen per cent for loss, the water available for 

 irrigation i» two hundred and sixty-eight cubic feet, which will irrigate 

 fifty-three thousand six hundred acres. If we suppose the irrigable 

 land to lie on one side of the canal, in a strip five miles wide, and that 

 the ground permits straight parallel primary ditches, spaced one mile 

 apart, it follows, that for each mile of canal there must bo five miles of 

 primary ditches, and that the quantity of irrigable land for each mile of 

 canal will be three thousand two hundred acres. Deducting one fourth 

 for laud not actually watered, we shall have two thousand four hundred 

 acres of irrigated laud for each mile of canal. Let us take a primary 

 ditch of capacity to carry fifty feet of water per second. Allowing for 

 loss, this size will be rather more than sufficient to cover more than the 

 two thousand four hundred acres with three inches of water, in seven 



