86 RELATIONS OF SOIL TO WATER 



fourteen inches high. A head of water two inches in height 

 was maintained on the top of each column throughout the 

 experiment. The results were as follows : 



Inches of Water passing in twenty-four hours 



Meshes per inch of Sieves used to prepare Sands. Clay Loam. Black Marsh. 



40-60 ... 60-80 ... 80-100 ... 100- 



Inches. Inches. Inches. Inches. Inches. Inches. 



301 ... 160 ... 73-2 ... 39-7 ... 1-6 ... 0-7 



This series of results serves excellently to illustrate the 

 fact, that the finer are the particles of a soil the slower will 

 be the rate of percolation through it. King remarks that the 

 whole of the rates of percolation observed are far above what 

 the same soils would yield in the field ; this is owing to the 

 shortness of the columns used, the absence of air in the inter- 

 stices, and the considerable head of water maintained. 



King (nth Wisconsin Report, 285) has also determined in 

 great detail the rate at which water drains from saturated 

 sands of various degrees of fineness. The sands, prepared 

 as before, were filled into tubes 8ft. long and 5 inches in 

 diameter ; each column was completely saturated with water 

 from below, and drainage was then allowed to commence. 

 All the sands contained nearly the same proportion of water 

 when saturated. Air was allowed to enter at the top of each 

 column, but precautions were taken to prev.ent evaporation. 



The amount of percolation in the first hour shows in the 

 most striking manner the different behaviour of the coarsest 

 and finest sand. The finer sands, retaining so much more 

 water at first, discharge after the first hour a little more than 

 the coarsest. At the end of nine days, regular percolation had 

 ceased in all the columns ; but from time to time slight per- 



