TEE DEPARTMENT OF AGRICULTURE 527 



and interactions; (3) discovery of normal tendencies toward enrich- 

 ment, physical, chemical and bacterial; (4) detection and elimination 

 of abnormal tendencies; and (5) prescription of treatment required 

 for regulating and intensifying the natural processes and thereby in- 

 creasing efficiency. The researches render it clear that the soil is the 

 product of uncounted eons of interaction between the organic and 

 inorganic; that the slow production of a soil is a process no less defi- 

 nite than the quicker production of a crop or a flora; that the process 

 may be brought wholly under human control; and that in view of in- 

 creasing population, the welfare of men and nations henceforth must 

 depend on the care and intelligence devoted to the maintenance and 

 improvement of this gift of the ages. 



The controlling condition of life and growth on the soil is climate, 

 especially that ever-varying temperature and moisture and air move- 

 ment forming weather. The first need concerning weather is fore- 

 knowledge (or prevision) definite enough to permit prediction; and 

 while the earlier investigations were directed to this end, they neces- 

 sarily included examination and classification of the atmosphere with 

 its aqueous vapor, and determinations of temperature, rainfall, vapor- 

 tension and other factors. Herein the usual course of progress was 

 reversed; commonly discovery of principles precedes both appreciation 

 and utilization of phenomena; but in weather work the need inspired 

 search for the principles — i. e., the ends led the means. With like 

 contrariety, the effort for control was directed not so much to the 

 natural factors of weather as to the movements of men and other 

 organisms in adjustment thereto — indeed even yet the wind bloweth 

 as it listeth, while men merely prepare to meet or escape its force. 

 Still, as the work progressed, both the constants and the caprices of 

 the air with its associated water were measured in such manner as not 

 only to permit prevision within reasonable limits, and thereby afford 

 practically useful weather prediction, but to yield definite knowledge 

 of a use extending far beyond the primary need. Thus, it has become 

 clear that in so far as life and growth are concerned the role of the 

 aqueous vapor is paramount; plants absorb and transpire water to an 

 amount usually exceeding many times their own volume during each 

 season; and their action affects not only the circulation of soil water 

 air below the surface, but the humidity of the air and the circulation 

 of both air and water about and above them. Again it appears that the 

 average rainfall of the United States is less than half that required 

 for full productivity in native and cultivated organisms ; yet that some 

 90 per cent, of the rain-water gathering into streams is wasted in 

 floods which annually wreak damage to an amount exceeding the esti- 

 mated cost of flood prevention, and this despite a large saving of life 

 and property by reason of flood warnings issued by the "Weathei 



