METHODS OF THE EARTH-SCIENCES. 67 



less agree without hesitation that the solid products of accurate and 

 complete observation, natural or experimental, are the bed-rock of our 

 group of sciences. The first great object sought by laudable methods 

 is, therefore, the promotion of the most accurate, searching, exhaustive 

 and unbiased observation that is possible. One of the primary efforts 

 in behalf of our sciences, therefore, was naturally directed to the task 

 of promoting the best observational work. It was soon discovered that 

 two chief dangers threatened the worker — bias and incompleteness. 

 To guard against the first there was evolved 



The Method of Colorless Observation. 



Under its guidance, the observer endeavors to keep his mind scru- 

 pulously free from prepossessions and favored views. However 

 tensely he may strain his observing powers to see what is to be seen, 

 he seeks solely a record of facts uncolored by preferences or prejudices. 

 To this end, he restrains himself from theoretical indulgence, and 

 modestly contents himself with being a recorder of nature. He does 

 not presume to be its interpreter and prophet. At length, in the 

 office, he gathers his observations into an assemblage, with such infer- 

 ences and interpretations as flow from them spontaneously, but even 

 then he guards himself against the prejudices of theoretical indulgence. 



Laudable as this method is in its avoidance of partiality, it is none 

 the less seriously defective. No one who goes into the field with a 

 mind merely receptive, or merely alert to see what presents itself, how- 

 ever nerved to a high effort, will return laden with all that might be 

 seen. Only a part of the elements and aspects of complex phenomena 

 present themselves at once to even the best observational minds. 

 Some parts of the complex are necessarily obscure. Some of the most 

 significant elements are liable to be unimpressive. These unobtrusive 

 but yet vital elements will certainly escape observation unless it is 

 forced to seek them out, and to seek them out diligently, acutely and 

 intensely. To make a reasonably complete set of observations, the 

 mind must not only see what spontaneously arrests its attention, but 

 it must immediately draw out from what it observes inferences, inter- 

 pretations, and hypotheses to promote further observations. It must 

 at once be seen that if a given inference is correct, certain collateral 

 phenomena must accompany it. If another inference be correct, cer- 

 tain other phenomena must accompany it. If still a third interpre- 

 tation be the true one, yet other phenomena must be present to give 

 proof of it. Once these suggestions have arisen, the observer seeks 

 out the phenomena that discriminate between them, and, under such 

 stimulus, phenomena that would otherwise have wholly escaped atten- 

 tion at once come into view because the eye has now been focused for 

 them. It may be affirmed with great confidence that without the 

 active and instantaneous use of these concurrent processes the observer 

 will rarely, if ever, record the whole of any one set of significant ele- 



