PREFACE. 



The great need of agricultural practices at the present 

 time is a keener appreciation and a more thorough com- 

 prehension of the principles which underlie them. The 

 facts of agriculture are spread through so many and widely 

 different fields, and are so numerous, that no one can hope 

 to grasp them all or needs to do so. But the laws and 

 principles which control his practice each farmer must 

 know before he can secure his re-suits with the greatest cer- 

 tainty and at the least cost. 



In these pages the aim has been to present to the student 

 who expects to be a farmer, some of the fundamental prin- 

 ciples he must understand to become successful. They 

 are presented from the standpoint of physics rather than 

 of chemistry or of biology, and in dealing with the physical 

 side of the problems the burden of effort has been to lead 

 the student to see WHY he should practice more than 

 WHAT, and it is hoped the student will pursue the various 

 subjects treated in this spirit, not only in his study, but 

 above all on the farm and in the field. 



The book has been written from "the standpoint of the 

 general student and farmer rather than that of more tech- 

 nical scientific agriculture and only so much of laboratory 

 methods and specific data of observation are given as may 

 serve to demonstrate the fundamental principles treated. 



F. H. KING. 

 University of Wisconsin, 



Madison, Wis., May, 1901. 



