It i.>^ seen that in drv seasons tliero is about half as much rain as in 

 \\v{. and that about one year in three has less than 75 per cent of the 

 normal rainfall. The follinving; table shows the monthly rainfall dur- 

 ini^ the crop-j^rowiiiij: months for the same period and is inserted to 

 show that even in seasons of normal or excessive rainfall, as in 1901 or 

 1903, there may be a dry month which will greatly retard grow^th. 



Monthly rainfall in Philadelphia from 1895 to l90Jf. 



WATER SUPPLY. 



Most of the irrigated meadow land in Pennsylvania lies near the 

 beds of small creeks fed by springs. The flow of the springs varies 

 considerably during the year, many of them dr\ing up, so that part 

 of the year the water supply is insufficient for irrigation, or ceases alto- 

 gether. Small dams constructed of timl)er back filled with earth are 

 built to raise the water sufficiently high to cover the land, but not for 

 storage. The}'^ are usually small affairs, cheaply constructed, costing 

 from $5 to $20. "Wlien washed out they are often not replaced for a 

 year or two, the land meanwhile going unirrigated. 



The use of wxlls as a source of irrigation is cjuite limited, and 

 throughout the East the absence of windmills is particularly notice- 

 able. The cost of well boring is considerabh' higher than in the 

 South and West. 



Many farmers near the large cities use city water for irrigation, 

 since, if the farm is small and the use of water is Hmited, it is thought 

 to be cheaper than pumping. The usual cost of such water is $1 to 

 $1.50 per 1,000 cubic feet, or $44 to $65 per acre-foot — a price which 

 would certainly seem prohibitive to western irrigators, some of whom 

 pay less than 1 per cent of these costs, and even wdiere pumping is 

 practiced, as in Santa Clara Valley, California, the average cost of 

 raising water 65 feet is only $4.4.0 per acre-foot, or 10 per cent of the 

 above price. The success of irrigation under the conditions found in 

 the East is due not to cheap water supply, but to the high value of 

 crops grown and the careful distribution of the small quantity of 

 water used. 



