PREFACE 



XI 



h drology of sub-soil water garnered by Mr. H. T. Ferrar, 

 of the local Survey Department, have provided a founda- 

 tion for discussions on this most important topic. 



I should like also to acknowledge the pains which 

 Prof. E. A. Gregory, the Editor of this series, has taken, 

 under all the disadvantages involved by my absence in 

 Egypt. 



The greater part of the work would not have been 

 executed had it not been for the assistance of my wife, 

 who has also helped me in preparing the present volume, 

 and in working up the records on which it is based. 



W. Lavtrence Balls. 

 Gezira House, 

 Cateo. 



