vi PREFACE 



The behaviour of actual soils under known conditions 

 has been made as far as possible the foundation of 

 the conclusions drawn. 



A great mass of results has accumulated from the 

 investigations made in the very numerous Agricul- 

 tural Experiment Stations in Europe and America ; 

 with these results the agricultural teacher is too often 

 unacquainted. His valid excuse is the scattered 

 publication of the reports, and his want of time to 

 correlate the several results recorded. The writer 

 hopes that the publication of these lectures will 

 stimulate others to labour in the abundant harvest 

 field of Experiment Station Reports. It must ever 

 be borne in mind that it is only on the results of 

 experimental investigations that Agricultural Science 

 can be safely built. 



The reader will probably be surprised that so little 

 is said respecting English soils, and so much respecting 

 the soils of America. The writer heartily wishes that 

 this might have been otherwise. In fact, however, the 

 physical constitution and properties of English soils 

 have as yet not been investigated, save in a very few 

 exceptional cases ; this has been doubtless due to the 

 great lack of investigators and research laboratories 

 in this country. The general properties of soils can of 

 course be equally well illustrated by any well studied 

 examples, but the deficiency of knowledge of our own 

 local soils is nevertheless a very real evil, and must 

 greatly hinder the practical application of general 

 principles. 



