24 IRRIGATION. 



6th. One inch of water flowing 4 miles per hour, equal 

 one and one-fifth quart per second. 



Hth. One quart per second, flowing for 24 hours, will 

 cover an acre five-sixths of an inch deep. 



8th. One inch of water flowing 4 miles an hour is equal 

 to 18 gallons per minute, or 1,080 gallons per hour. 



Wi. An artesian well, 6 inches in diameter, would give 

 a stream of 28 square inches, and would deliver 32 quarts 

 per second, if the flow were at the rate of 4 miles an hour. 



10th. Such a well would furnish an inch of water per 

 day for 28 acres, or an inch a week for 196 acres, which 

 would be a very insufficient quantity to irrigate dry open 

 soils in places where the climate is arid. 



llth. The cost of such a well would he at least $5,000 

 to $10,000,. or more than the value of the land when 

 irrigated. 



The estimates made by various authorities upon irriga- 

 tion, as to the quantity of water needed, vary consider- 

 ably. As a rule, the quantity of water used by some 

 irrigators, would seem to be extravagant. Thus we find 

 standard authorities upon irrigation, and practical irriga- 

 tors, recommending and using quantities of water vary- 

 ing from one to four quarts per second, continuously 

 flowing for 24 hours for each acre, at intervals of from 

 five to fourteen days. It is evident, however, that the 

 quantity of water needed to moisten the soil thoroughly, 

 depends on certain conditions, which are very variable. 



These conditions are : 



First the nature of the soil. 



Second the character of the climate. 



Third the nature of the subsoil. 



As to the Soil. Soils differ greatly in their power to 

 absorb and retain water. Those which absorb most wa- 

 ter retain it for the longest time. The power of absorp- 

 tion is due to the surface attraction of the particles of 

 soil for water. The finer the particles of the soil, the 



