250 Ground Water, Wells and Farm Drainage. 



abundant supplies of water can always be found in such 

 places. 



The loose sands and gravels have a pore space of 20 to 



FJO. 88. Contour map of a field, one portion of which has beeii tile 



drained. 



38 per cent, of their volume so that where these lie below 

 the ground water surface and their volume is large an 

 abundance of water exists. 



