THE DISCIPLINARY VALUE OF GEOGRAPHY 109 



tions, distances and altitudes, and the preparation of maps of appropri- 

 ate scales, along with an empirical description of the facts observed. 

 For those geographers, however, who, in these modem days, enter 

 whole-souled into the explanatory method of describing land forms, 

 there is needed, in addition to all the earlier requirements — for every 

 modern geographer ought to be well exercised in the preparation of 

 empirical descriptions, as well as in the arts of surveying and cartog- 

 raphy — a careful and conscious training in theoretical investigation; 

 because every explanatory description, in so far as it introduces the 

 supposed facts of the past as the best means of describing the visible 

 facts of the present, goes beyond observation and employs theories; 

 and theories can be successfully established only by the critical use of 

 scientific methods of investigation. 



The different mental processes involved in an investigation of the 

 kind with which we are here concerned may be arranged as follows: 

 observation and record of accessible facts ; induction of generalizations ; 

 search for fuller explanation; invention of hypotheses or supposed 

 mental counterparts of invisible facts; deduction of consequences from 

 each of the invented hypotheses; confrontation of the consequences 

 with appropriate facts; preliminary judgment; revision and improve- 

 ment of each process; final judgment of the degree of correctness of 

 various invented hypotheses. 



Observation and Record of Accessible Facts. — The first step in a 

 problem is the acquisition of a certain number of facts. This may 

 involve original observation, as in the outdoor exploration of a geo- 

 graphical field, or it may be based on second-hand observation, as in 

 the study of some other observer's records in books and maps. In 

 either case, the investigator must be alert to avoid deception by mis- 

 taken appearances and by misleading subjective sensations ; at the same 

 time the mind must be kept sensitive to every real impression, to which 

 it must respond in the most docile manner, submissively recognizing 

 the facts as they stand, not constraining them in the least one way or 

 the other. The investigator must be untiringly active in traversing 

 his outdoor field, and omnivorous in devouring all pertinent material 

 in the library. Indeed during the process of acquisition, outdoors and 

 indoors, the investigator's mind must be like a fresh and sensitive pho- 

 tographic plate, on which no previous impressions blur the new ones 

 that are made on it. 



The facts mentally acquired must in some way, graphic or verbal, 

 be recorded; and at the outset the records should be made in colorless 

 empirical form, as free as possible from theoretical prepossessions. It 

 will be chiefly in proportion to the larger or smaller measure of pre- 

 viously acquired experience that the observer will, at this early stage of 

 his study, employ roundabout phrases or technical terms in recording 



