122 



RELATIONS OF SOIL TO WATER 



that received at Rothamsted. The turf evaporates the whole 

 of the summer rainfall, percolation only occurring in very 

 heavy storms. In three summers during Sir John Evans' 

 experiments, the rainfall in six months amounted to 15-16 

 inches ; yet in two of these summers no percolation occurred 

 through the turfed soil. The rainfall has thus been insufficient 

 to show the full evaporating power of the turf. In the 

 winter months, when a greater excess of water is available, 

 the turf has evaporated considerably more than the water- 

 surface. 



TABLE XXII 



EVAPORATION AND PERCOLATION UNDER VARIOUS 

 CIRCUMSTANCES 



Another comparison of turf with bare soil is afforded by 

 the results of the drain-gauges, three feet deep, established 

 for four years, 1883-6, at the Experimental Station, Geneva, 

 New York. 



The rainfall in this case was again far too small to exhibit 

 the evaporating power of the turf. 



1 Average of fourteen years. 3 Average of twenty years. 



3 Average of fifteen years. 



