ARE MADE. 



These are merely illustrative experiments, such as the chemical 

 lecturer makes before the audience he is instructing. 



In the second case, they are intended to try alleged facts ; to 

 test hypotheses ; to determine whether observations said to have 

 been made have been made correctly ; whether conjectures 

 thrown out have any foundation in truth,; whether theories pro- 

 pounded are deserving of a place in our books, or ought to be 

 banished altogether from their pages. These researches of the 

 experimental critic are as valuable and important as any which 

 can be made. To them we must be indebted for clearing away 

 much rubbish which at present finds a place in our works upon 

 scientific and practical agriculture. 



In the third case, they are intended to discover new proper- 

 ties, relations, and useful applications of bodies ; to determine 

 more accurately and more fully the circumstances by which 

 these relations and applications are modified ; and thus to help 

 us forward to the establishment of new or more general theo- 

 retical principles, and of new practical deductions. 



To these last the term research most strictly applies, though, 

 with a view to both the second and the third of the objects 

 specified above, experiments in the field and the feeding-house 

 are fitted to render much service to the arts of rural life. 



In suggesting the experiments proposed in the following 

 pages, it has been my intention, among other things, 



First, To bring into view the numerous weak, or doubtful, 

 or altogether dark points in our present knowledge of agricul- 

 tural theory ; and, 



Second, Critically to consider the bases on which our opinions 

 in reference to many practical points really rest. Weak points 

 in theory, and uncertainties in practice, ought to be fairly stated 

 and considered. Instead of being covered over and hidden by 

 confident assertion, they ought to be made the subject of experi- 

 ment in the field or in the feeding-house, and of analytical re- 

 search in the laboratory. It is to field and feeding experiments 

 that I intend principally to confine the attention of my readers 

 in what is to follow, though I shall not fail to indicate from time 

 to time those experimental researches in the laboratory which 

 appear most urgently to be required. 



