INTRODUCTION 



THE physical properties of soil, and their bearing upon its 

 fertility, is a subject which has been much neglected by the 

 scientific investigator till quite recent years. The horticulturist 

 and farmer have indeed from the earliest times realized the 

 immense importance of a favourable texture of the soil, if 

 crops were to be successfully grown. The special suitability 

 of certain soils for certain crops, and the striking results 

 which can be produced by skilful tillage, have always formed 

 part of the inherited experience of agricultural art. In works 

 dealing with practical agriculture, tillage operations have 

 always occupied a prominent place. 



The only early investigation on soil physics is that of 

 Schubler, made more than sixty years ago. His work was 

 comprehensive in its scope, and in general very accurate. At 

 the present day his results still furnish some of the favourite 

 quotations of our agricultural textbooks. 



The rapid rise of agricultural chemistry in the middle of 

 the present century diverted attention from the importance of 

 such investigations. When it was realized that a chemist 

 could analyse a crop and ascertain the elements of which it 

 was composed, and then analyse the soil and ascertain what 



