Contents. 



GROUND WATER, WELLS AND FARM DRAINAGE 



CHAPTER XII. 

 MOVEMENTS OF GROUND WATEB. 



PAGE. 



AMOUNT STORED IN GROUND 



Ground water surface, p. 258 ; Seepage, p. 258 ; Growth of "streams, 



p. 259 ; Rise of ground water through precipitation, p. 260 ; 



Law of flow through sands, p. 262 ; Calculatipn of flow, p. 262 ; 



Observed and computed flow, p. 264 ; Relation of rate of flow to 



diameter, p. 266 ; Relation of pressure to flow, p. 266 ; Observed 



rates of flow in sand and rock, p. 268 ; General movements 



across wide areas, p. 270. 



FLUCTUATIONS IN THE RATE OF FLOW OF GROUND WATER 270 



Due to barometric changes, p. 270 ; In springs, p. 270 : In rate of 



discharge from tile drains, p. 271 ; Change of level in wells, p. 



272 ; Due to changes in soil temperature, p. 271. 



CHAPTER XIII. 

 FARM WELLS. 



ESSENTIAL FEATURES OF A GOOD WELL .. 275 



Capacity, p. 275 ; Best geological conditions, p. 276 ; Depth, p. 283. 



CONDITIONS INFLUENCING CAPACITY 276 



Size of grains and pore space, p. 276 : Depth in water-bearing beds, 

 p. 278 ; Pressure, p. 279 ; Diameter of well, p. 279. 



USB OF SAND STRAINERS ........ 281 



Capacity, p. 281 ; Compared with open well, p. 282. 



TEMPERATURE OF WELL WATER 284 



WELL CASINO AND TOP 284 



CHAPTER XIV. 

 PRINCIPLES OF FARM DRAINAGD. 



NECESSITY FOR DRAINAGE 28i> 



CONDITIONS REQUIRING DRAINAGE 2S " 



ADVANTAGE OF DRAINAGE 287 



Increases' root room, p. 287; Increases available moisture, p. 288; 

 Makes soil warmer, p. 288 ; Better ventilation, p. 290. 



TILE DRAINS 290 



Essential features of drain tile, p. 291 ; How water enters tile, 

 p. 292 ; Collars, p. 292 ; Depth laid, p. 292 ; Distance between 

 tile drains, p. 296. 



CONFORMATION OF GROUND WATER ABOUT DRAINS "91 



Rise away from drains, p. 293 ; Observed ground water surface, p. 

 296 : Rate of change of surface, p. 297. 



