324 



CITRUS FRUITS AND THEIR CULTURE. 



the plane at which it entered. Now, it is not improba- 

 ble that the lakes in the higher sections of Florida are 

 the source of many artesian wells. Numbers of these 

 lakes are not drained by rivers or streams and have no 

 visible outlet, but in a number of cases they have 

 been entirely emptied for a time, by the disap- 



Fig. 72. Diagram showing how artesian wells are formed. A, lake. 

 B, pervious layer of rock. C, artesian well. 



pearance of the water through an opening in 

 the bottom. It is probable that water frequently 

 escapes constantly through a pervious stratum lo- 

 cated in the bottom or opening into the side. Fig. 72 

 shows how this might be. Opening into the lake, A., is 

 a pervious layer, B., located between two impervious 

 layers into which the water passes. The water following 

 the dip in the strata flows downward, and if a well is 

 bored at C., the water will rise above the surface. The 

 Florida wells are usually between forty and two hun- 

 dred and fifty feet deep, though some are even deeper. 

 From this it will be seen that irrigation from artesian 

 wells is feasible onlv on the lower levels. 



PUMPING WATER. 



The higher grounds can, however, be irrigated by 

 pumping from wells or lakes. Many lakes are located on 

 the higher levels. In the vicinity of Lake City, two hun- 



