and interactions; (3) discovery of normal tendencies toward enrichment, 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 increasing 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 definite 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 increasing 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 movement forming weather. The first need concerning weather is foreknowledge (or prevision) definite enough to permit prediction; and while the earlier investigations were directed to this end, they necessarily 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 estimated cost of flood prevention, and this despite a large saving of life and property by reason of flood warnings issued by the Weather
