and Subterranean Water Storage. 83 



mean range of temperature, must affect the mean annual rainfall. 

 Drainage necessarily assists this action. It not only clears the 

 surface of moisture still more rapidly than before, but it even 

 carries off much of the water that had actually entered the soil 

 and was on its way to the rock. Thus drainage affects the 

 springs as well as the rainfall, and doubles the result. 



And although it is true that the rainfall in England depends 

 very largely on the physical conditions of the British islands— 

 on the vicinity, not only of a great ocean, but of a great and 

 warm current of water and moist air crossing that ocean — on 

 the presence of a mountain chain of moderate elevation on the 

 western side of the island — on the general form of the land — on 

 the adjacent lands of the continent of Europe — and on many 

 other facts — still neither the total amount nor the distribution 

 can fail to be influenced by those important and powerful causes 

 to which I have directed attention. An alteration of a fraction 

 of an inch per annum in the mean rainfall, the addition of an 

 inch in the summer fall counterbalanced by the reduction of an 

 inch in that of the winter months — these ma}' seem trifling, but 

 if persistent they effect a real change of climate, and one which 

 will in time show itself in the vegetable and animal productions 

 that flourish under it. 



V. — ECONOMISATION OF WaTER SuPPLY. 



The practical value to the agriculturist of all that has been 

 said on the subject of rainfall and water storage, and the results 

 of cultivation on water supply, can best be measured by the 

 extent to which he may hope to make use of such knowledge, 

 either by adapting his methods of cultivation so as to take advan- 

 tage of the result of change, or by enabling him to produce a 

 modified climate, availing himself of natural causes of change. 

 Incidentally he may also learn in this way the means of 

 utilising and economising the supply of rain that comes to him 

 in the ordinary course of nature. 



I think it will be evident, from all that has been said under 

 the last heading of this article, that where all forests have been 

 removed over large districts a combination of tree-cultivation 

 with ordinary crops is calculated to equalise its summer and 

 winter climates, to increase the yield from springs, and to restore 

 to some extent the former conditions of climate. At the same 

 time it must be remembered that in many respects the climate 

 of England has been ameliorated rather than injured by the 

 alterations that have taken place ; and that with us there must 

 always be so large a rainfall that there is not the same need 

 for this modification as in other countries of Europe, where 



G 2 



