42 



OBSERVATIONS TO BE MADE. 



cation to the land. Thus, if four substances, 1, 2, 3, 4, are to 

 be tried on as many quarter acres, a square or oblong of two 

 acres might be subdivided as follows : 



3. What observations ought to be made, and hoic. 



In all experiments, the immediate, as well as the ultimate, 

 effects and appearances should be observed and recorded. 

 At intervals, also, between these two periods, the effects and 

 appearances should be examined and noted down, as these 

 intermediate observations are often very instructive. Im^ 

 portant changes of weather should likewise be registered. In 

 field experiments, the weather which may promote the action 

 of one substance may diminish that of another. In feeding, 

 also, the temperature is an element in which extreme oscilla- 

 tions not only affect all animals, but which influence some 

 animals more than others, and thus modify the action of the 

 food they eat. 



These observations should not only be all made with much 

 care and conscientiousness, but they should, as far as possible, 

 be made by the chief experimenter, and recorded by himself. 

 He ought, also, to guard against the possible influence of any 

 preconceived opinion, whether theoretical or professional, which 

 may insensibly act upon his mind. 



The most enlightened and the best educated are not free from 

 the possibility of such a bias. And, in regard to such a possible 

 bias, practical men -are exceedingly suspicious, especially when 

 deductions, in reference to practical subjects, are drawn by 

 scientific men. Hence they receive, with doubt and coolness, 

 the recommendations of science supposing the man of science, 

 if not ignorantly prejudiced, to be professionally influenced in 



