THE BEGINNINGS OF EXPERIMENTATION 53 



The first voyage of Columbus was an experiment. 

 It is not always that experiments may be performed in 

 the laboratory, for many of them must be on a national 

 or world-wide scale, as is true to-day of many social 

 experiments. Sometimes the by-products of an ex- 

 periment are themselves of great value. An illustra- 

 tion of this is Columbus's discovery of the variation 

 of the magnetic declination. 1 Not always, of course, 

 are the by-products of the main experiment so evident 

 as they were in this case of Columbus's first voyage ; 

 nor are they so overshadowed by the importance of 

 the main result. In such by-products may be the 

 greatest value of the experiment. While the result 

 of the main experiment is usually the reward of clear 

 thinking and precise manipulation of the experimental 

 apparatus, the by-products are usually the reward 

 of a comprehending observation. They are frequently 

 the basis of important inventions, but they are not 

 obtained by the unobserving, who pass over their 

 indications. 



Three qualifications for an experimenter are thus 

 suggested : (1) clear thinking, (2) accurate experi- 

 mentation, and (3) careful observation. The first is 

 required before the experiment, in order that experi- 

 mental conditions may be devised which will permit 

 of a definite answer to the question under examina- 

 tion. The second demands that the measurements be 

 sufficiently precise not to obscure the desired results. 

 There must also be a careful observation during the 



1 The angle between the direction assumed by a compass needle 

 and the geographical meridian is called the magnetic declination of 

 a locality. 



