80 PART II SOME IMPORTANT METHODOLOGICAL TERMS. 



SECTION X. -EXPERIMENT AND USE OF INSTRUMENTS. 



25. A decided approach towards experiment is made 

 where an action is intentionally performed in order to ascertain 

 the results where, for instance, I seek to recall a landscape 

 for the purpose of observing what can be recalled; where I 

 shut my eyes to note whether anything is visible with eyes 

 closed; where I pull at a heavy piece of furniture to study 

 the nature of the feeling of effort; where I pinch myself to 

 learn something concerning pain; where, with one hand, I play 

 with two pebbles for some time, throwing them successively 

 up into the air, and endeavour to catch them in the same hand 

 as they fall, in order to learn something of the development of a 

 habit; where I speak now gently and now sternly to a child, 

 to the end of determining which course is the most effectual; 

 and so on. 



Experiments of this order are unsystematic in nature, and 

 the proof lacks exact determination. They are experiments 

 belonging to the pre-scientific stage, and only become veritably 

 trustworthy when the conditions are clearly defined and 

 systematically varied. Scientific experiment, in other words, 

 is systematic observation under conditions as far as possible 

 precisely defined and systematically varied and measured. 

 When, for example, we combine certain known chemical 

 elements present in a known proportion by means of special 

 apparatus which enables us to obtain exact quantitative results, 

 we experiment, in the scientific sense of the term. 1 The value 

 of such quantitative ' determination is often one of indirect 

 importance, inasmuch as its object may be to lend precision 

 to a statement which might aid us in obtaining reliable de- 

 ductions. 



Pre-scientific experiments have, as a rule, relatively small 

 scientific value. On the other hand, methodical observation 

 closely approaches scientific experiment. To examine a plant 

 species in the sunlight, in the shade, at night, when it is 

 raining, in varying temperatures, soils, altitudes, and climates, 

 and at different seasons, is virtually equivalent to producing 

 the conditions artificially. It was, therefore, an inadequate 

 conception of the process of observation which condemned 

 observation as being wellnigh useless and unscientific, whilst 

 lauding to the skies the employment of experiment. The 

 genuine comparison is between pre-scientific observation and 

 pre-scientific experiment; and if this be conceded, indiscriminate 

 contempt for observation is as gratuitous as indiscriminate 

 commendation of experiment.- Scientific experiment forms an 



1 Jevons has several excellent chapters on quantitative determination in 

 his Principles of Science. 



- "At Greenwich Observatory in the present day, the hundredth part of 

 a second is not thought an inconsiderable portion of time. The ancient 



