AUTHOR'S PREFACE 

 TO THE THIRD EDITION. 



Majvy views and principles which I had endeavored to develops 

 in reference to nutrition, and especially to the cultivation of 

 vegetables, were strongly opposed, immediately on the appeaV- 

 ance of the first edition of this Work. I could not, however, 

 resolve to make any material change in the immediately succeed- 

 ing edition, because I did not consider the scientific investigation 

 of the important questions at issue as completed, and because I 

 thought that I ought to trust the decision of them to experience 

 alone. 



Many of the objections raised were founded upon a want of 

 mutual understanding ; others related to positions and assertions 

 having no connexion with the peculiar object of the book. I 

 have set these aside by the omission of all passages thus called 

 in question. 



In the three years which have elapsed between this edition and 

 the first, I have not neglected any opportunity of subjecting to a 

 rigorous and careful examination the principles which I had 

 developed of the nutritive properties of plants, and their applica- 

 tion to agriculture. I have endeavored to make myself acquainted 

 with the condition of practical farming, and with what it requires, 

 by a journey through the agricultural districts of England and 

 Scotland ; and during this interval a long series of experiments 



