816 



SCIENCE 



[N. S. Vol. XXXIV. No. 885 



try available for water supply and naviga- 

 tion no less than power are interrelated 

 through the ground-water reservoir in 

 such wise that the regimen of each is de- 

 pendent on the integrity of the ground re- 

 serve by which it is chiefly maintained. 

 The essence of a stream resides in its con- 

 tinuity of flow; and this continuity of 

 flow is in nature due absolutely and wholly 

 to continuous supply from the store of 

 ground-water. 



12. Since the water vapor which bathes 

 the continent and tempers its climate is not 

 all precipitated on the land over which it 

 passes, but in part goes on over adjacent 

 seas; since the part precipitated as rain 

 and snow and distilled as dew is largely re- 

 evaporated from soil and open water, espe- 

 cially from growing plants whose vitality 

 it sustains; since the residuum mainly 

 soaks into the earth (and should do so 

 wholly, in order to retain the best natural 

 and artificial balance) where it forms a 

 reserve store of ground water for a period 

 averaging perhaps ten years; and since 

 streams are fed chiefly — under the best 

 conditions wholly — from this ground- 

 water reserve, it follows that the fresh 

 water of the country, as a whole, in its 

 forms of vapor, rain, snow, dew, ground- 

 water, lake and stream, is essentially a 

 grand physical unit made up of interde- 

 pendent parts, and that each stream, 

 despite its essential unity and the interre- 

 lation of all its parts, is but an integer 

 within the larger unit. 



RELATIONS IN EQUITY 



13. Water is the prime necessary of life. 

 Fully five sixths of human food, and in- 

 deed a like proportion of the human body, 

 consists of HgO or water, chiefly in its 

 simple form, partly in chemical combina- 

 tions. In the human organism water is es- 

 sential to assimilation, to metabolism or 



structural growth, to reproduction — in- 

 deed it would appear that no vital process 

 occurs in the absence of water or otherwise 

 than as a manifestation of its inherent 

 properties. In the plants and lower ani- 

 mals yielding human food and clothing, 

 water plays an equally essential role — in- 

 deed without water the continent would 

 be unproductive and uninhabitable, and 

 the lands of the planet but a dead world. 

 14. In this as in other countries, water 

 is the primary natural resource. Indus- 

 trial and other forms of activity on which 

 rest the power and growth of peoples and 

 states depend absolutely on the mainten- 

 ance of human life and population, which 

 in turn depend on food and measurably on 

 apparel; and whatever its breadth in land 

 and wealth in minerals, no continent can 

 sustain human life and population without 

 sufficient water for drink and for produc- 

 ing from the soil the materials for solid 

 food and clothing. The average crop plant 

 transpires 450 times the weight of its own 

 (dry) substance in water during its 

 growth; and reckoning evaporation from 

 the soil of the moisture required to main- 

 tain proper texture, the agricultural duty 

 of water is to produce one thousandth of 

 its weight in average plant crop, or one 

 four-thousandth in grain, or perhaps one 

 forty-thousandth in meat.^ Under rigid 

 economy an adult human worker may be 

 sustained for a year by 200 pounds each of 

 bread and meat, with 2,000 pounds of 

 water for drink; or, since the bread and 

 meat require for their production respec- 

 tively 400 tons and 4,000 tons of water, 

 something over 4,400 tons of water in 

 direct sustentation, apart from that re- 

 quired for ablution and for melioration of 

 climate through aqueous vapor in the air. 



= "The Agricultural Duty of Water," U. S. 

 Department of Agriculture Yearbook for 1910, pp. 

 169-176. 



