Preface to the Fourth Revision, v. 



no apology seems needed for the cross references which 

 frequently appear ; their object is to enable the student 

 to bring at once together all the scattered facts and 

 statements bearing upon the subject under discussion. 



The metric system has been employed to some 

 extent, as well as the ordinary English weights and 

 measures. The former has been used chiefly for the 

 expression of scientific ideas, the latter for practical 

 purposes. 



It is undoubtedly true that as science advances it 

 becomes more complicated, and less capable of appre- 

 ciation by the general reader. The modern student 

 needs a more thorough training than one of bygone 

 years, if he is to be able to grasp and put to practical 

 use the new facts and ideas which scientific investi- 

 gations are continually bringing forward. Agricultural 

 education must proceed side by side with scientific 

 research, if the latter is to be turned to any practical 

 use by the farmer. 



E. WAKINGTON. 



Harpendbn, 



September, 1902 



