194 WJMCGEE OUTLI^'ES OF HYDROLOGY 



to man, yielding an orderly series of sciences ranging from astronomy to 

 anthropology. In the coiirse of the progress two factors have prevailed: 

 first (in significance rather than order), the ceaseless and ever-growing 

 desire to know merely for the sake of knowing — that is, the spontaneous 

 interadjustment of mentality with external nature; and, second (in im- 

 portance, though often first in order), the conscious or unconscious habit 

 of utilizing knowledge — that is, the endless interadjustment between man 

 and external nature ; and under the infliience of these factors the sciences 

 and the applications of science have come up concurrently, sometimes the 

 one and again the other in the lead. Especially in the domain of the 

 natural sciences, habit commonly precedes thought and the object-matter 

 is used before the science is framed ; so plants were utilized before phytol- 

 ogy, animals before zoology, rocks and minerals before geology; so, too, 

 descriptive aspects have generally arisen the earlier, as geography before 

 geology and ethnography before ethnology; and in general the progress 

 in systemization has responded to the demands for knowing and for ap- 

 plying jointly. 



Now among the objects-matter of knowledge, none are more vital than 

 water : It is in accord with its nearness to human interest that it was late 

 to receive close attention, and that even yet it has received little thought 

 save in the descriptive aspect of hydrography; yet the habit of utilizing 

 and applying it, which arose unwittingly in the unwritten past, has 

 spread so widely and become so large a part of modern life as to warrant 

 concentrated and conscious consideration. Accordingly, in the light of 

 the long course of the development of the sciences, in the light of the 

 transcendent importance of the water of the earth to human welfare, and 

 in the light of the inherent interest of the object-matter itself, it would 

 seem clear that the time is ripe for establishing definitely the Science of 

 "Water, already known somewhat vaguely as hydrology. 



The relations of hydrology with other sciences would naturally corre- 

 spond with the relations existing among these others. It would derive 

 method from the chiefly formal or subjective sciences (mathematics per- 

 taining to quantities, astronomy pertaining to masses, chemistry pertain- 

 ing to substances, and physics pertaining to forces, with their several 

 subdivisions and ramifications) ; it would share object-matter with the 

 chiefly natural or objective sciences (meteorology pertaining to air, geol- 

 ogy pertaining to rocks, phytology pertaining to plants, zoology pertain- 

 ing to animals, and anthropology pertaining to men, with their several 

 and various subdivisions and combinations) ; and in some measure it 

 would tend to unite the two groups. The relations would be particularly 

 close with geology and meteorology, since water is at once a terrestrial 



