708 EXPEEIMENT STATION RECORD. 



results of the comparisons in a given experiment are fairly com- 

 parable one with another, but not directly comparable with those 

 in other trials, where the combination must necessarily be different. 

 They report the findings under a given set of conditions, which may 

 not recur completely another year or in another locality. Most of 

 them are influenced by factors which it is impossible for the ex- 

 perimenter to take full account of, because he does not know the 

 measure of them. The conditions of experiment differ therefore 

 from the control conditions of the laboratory. 



The aim of many experiments is to get a relatively quick result, 

 without resorting to the precision and detail of thoroughgoing in- 

 vestigation. In many cases this meets the immediate need of the 

 problem and of practice. To know that fall plowing, for example, 

 better prepares the land in a given locality for a particular crop is 

 quite sufficient, and to determine just why this is true would prob- 

 ably involve a more intricate series of investigations than we are at 

 pre.sent able to carn^ out, there are so many factors of soil, moisture, 

 biology, and chemical and physical change to be taken into account. 

 On the other hand, many classes of experiments are of such a kind 

 or have been so often repeated and checked under varying condi- 

 tions that quite broad generalizations may be drawn from them. 



Taken as a whole, this grade of inquiry has been of inestimable 

 service to American agriculture, in developing practical methods, 

 leading to a broader understanding, and making farming a more 

 intellectual and profitable occupation. There is still need for work 

 of this class and provision is made for it in the federal appropria- 

 tions. For many years to come it will very properly constitute a 

 large share of experiment station effort.. 



But, like research, it should be progressive, recognizing that ad- 

 vancement depends on building upon the things that have become 

 known. After a certain number of experiments on a given topic have 

 been made it is well to consider whether it is worth while to con- 

 tinue them. In certain classes of such work there is an endless 

 number of different combinations which may be made, but most of 

 these may give no new results of value. The experimenter using 

 public funds should be careful not to extend such work beyond what 

 is actually needed. At the present stage we must regard certain 

 facts as practically established, in so far as it is possible to establish 

 them by the methods employed, and direct our effort to other lines 

 of inquiry, rather than move in circles. The methods, also, should 

 be progressive, in order that gradually questions may be dealt \^dth 

 in a way to give a more enduring and intelligent answer ; and, finally, 

 these expeiTments, whose limitations are recognized, will often sug- 

 gest subjects for systematic research. For we need a broader founda- 



