LAYER OF PRACTICAL KNOWLEDGE. 71 



reach the truth, though a single experiment may lead to entirely 

 erroneous results. 



But these experiments ought to convince us that much of 

 what we now rely upon as agricultural experiments made to 

 establish special points as to manures, seeding, and feeding of 

 stock, is of little worth, because tinctured with error, and be- 

 cause the records of the experiments are so defective that the 

 shrewdest interpreter of facts can seldom find means for detect- 

 ing and eliminating the errors. 



These results also show us that it is only by a series of ex- 

 periments of the same kind repeated year after year, at the 

 same place and by the same trained observers, that we can hope 

 to secure data for trustworthy generalizations in agricultural 

 science. 



It would seem that common sense would teach any man that 

 it would be the best and cheapest method, if not one absolutely 

 essential, for reaching correct results, to have some place in 

 every State where such experimenting can bo done in the best 

 manner. This is just the want which our Agricultural Colleges 

 are fitted to supply. They can do this work for every State. 

 They can send forth men trained to observe, and with knowledge 

 enough of the difficulties in the way to save themselves and 

 their neighbors from the necessity of making experiments as 

 useless from their want of relation to others, as it would be to 

 test the temperature of Pittsfield in January, to learn whether 

 Indian corn would ripen there in September. 



There is in agriculture a sound layer of practical knowledge, 

 the common property of those best acquainted with the subject, 

 and on many points where the conditions are few, much advance 

 has been made within a few years. But the advance has been 

 more in horticulture than in agriculture, and in both of them 

 the advance has been more in improving kinds by selection than 

 in any other way. This principle of selection is now well 

 understood, and in the hands of skilful florists, pomologists and 

 breeders, it has accomplished great results in securing improved 

 forms of fruits and animals. Advance has been made in particu- 

 lar localities in regard to certain crops, and in those places men 

 believe that certain principles are established, and so they are 

 for them. But let them go to Wisconsin, or New Mexico, or 

 California, and perchance these same men will utterly fail in 



