INTRODUCTION vn 



unsurveyed a field as the study of the soil still presents, 

 must arrive at certain personal conclusions, and I have 

 tried to steer a middle course between an over insistence 

 on these points on the one hand, and the colourlessness 

 that would come from their entire exclusion on the 

 other. No great part of a text-book can pretend to 

 be original, but in the sections dealing with the 

 chemical analysis and the physics of the soil, I have 

 incorporated a good many unpublished measurements 

 and observations ; for the mass of the results on which 

 the book is based, I am chiefly indebted to the work 

 of Lawes and Gilbert, as set out in the Rothamsted 

 Memoirs, and to the writings of Warington in this 

 country, of King, Hilgard, and Whitney in America, 

 of Wollny in Munich. 



I have to thank Professor J. Percival, of the South- 

 Eastern Agricultural College, for notes respecting the 

 association of plants with specific soils, and many 

 suggestions on biological questions ; Major Hanbury 

 Brown, C.M.G., head of the Egyptian Irrigation 

 Department, for information concerning " salted " lands 

 in Egypt ; Mr F. J. Plymen, who has been associated 

 with me in carrying out a soil survey of the counties 

 of Kent and Surrey, and has executed many of the 

 observations recorded here ; Mr W. H. Aston, one of 

 my pupils, to whom I owe the observations on p. 153; 

 and finally, Dr J. A. Voelcker, to whom I am greatly 

 indebted for reading the proof-sheets, and making 

 many valuable suggestions thereon. 



A. D. HALL. 



Harpenden, December 1902. 



