SECTION IV 



CHAPTER X 



ECONOMICS* 



WITHIN the limits of this volume we can do no more than 

 glance at the many matters of economic interest to which 

 those researches are linked. Their most direct and im- 

 mediate application has been found in the Sub- Soil Water 

 controversy, from which many of the inquiries originated. 

 No attempt has here been made to emphasise the economic 

 importance of root asphyxiation and restriction, but the 

 text and diagrams should show that a deep water-table 

 is essential, and that a rise of the water-table to the roots 

 is deadly in July, prejudicial in September, and almost 

 harmless in December. For several years the yield per 

 acre in Egypt had been lessening (Fig. 71), and many 

 causes 24 had been invoked to account for it, but the matter 

 was obscure until Mr. J. R. Gibson, assisted by M. 

 Audebeau, showed that the level of the water-table had 

 risen on the State Domains, and pointed out the pro- 

 bability that such a rise, produced by improvements in the 

 system of irrigation, might suffice as a general cause. 13 ' 15 

 Mr. Gibson's death deprived the author of his collaboration 



* See Todd, J. A., for discussion of the purely economic problems of 

 cotton in Egypt and Lancashire. 



176 



