The Physical Basis of SocietyD. Appleton, 1916 - 406 من الصفحات |
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الصفحة 52
Carl Kelsey. or about five acres . It being estimated that one acre of grass furnishes 6,400 quarts of water in twenty - four hours , this tree supplied some 32,000 quarts of water daily . The influence of forests is very large . They ...
Carl Kelsey. or about five acres . It being estimated that one acre of grass furnishes 6,400 quarts of water in twenty - four hours , this tree supplied some 32,000 quarts of water daily . The influence of forests is very large . They ...
الصفحة 55
... acre of soil Darwin showed that there were from 50,000 to 500,000 earthworms , each of which passed through its body some 20 ounces of earth a year . On two square yards studied by Darwin the amount equaled 6.75 pounds and 8.38 pounds ...
... acre of soil Darwin showed that there were from 50,000 to 500,000 earthworms , each of which passed through its body some 20 ounces of earth a year . On two square yards studied by Darwin the amount equaled 6.75 pounds and 8.38 pounds ...
الصفحة 79
... acre , their holes numbering about 24,000 per acre . During the summer they ruined one - third of the alfalfa , totally destroying many fields , 15,000 out of 20,000 acres having to be replanted . They destroyed three - fourths of the ...
... acre , their holes numbering about 24,000 per acre . During the summer they ruined one - third of the alfalfa , totally destroying many fields , 15,000 out of 20,000 acres having to be replanted . They destroyed three - fourths of the ...
الصفحة 84
... acres of wild land is also open to question . The influence of the incoming white man upon birds deserves attention . Until the nineteenth century man did not make any serious inroads , directly at least , on the number of birds . The ...
... acres of wild land is also open to question . The influence of the incoming white man upon birds deserves attention . Until the nineteenth century man did not make any serious inroads , directly at least , on the number of birds . The ...
الصفحة 87
... acre of improved land , a sum larger than the total tax collected on the same land for local or state purposes . Yet birds are an important factor in reducing insect pests , for , as some one has said , they " reduce to a lower level ...
... acre of improved land , a sum larger than the total tax collected on the same land for local or state purposes . Yet birds are an important factor in reducing insect pests , for , as some one has said , they " reduce to a lower level ...
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