CONSUMPTION, AND CONSERVATION 1. Changes in the land supply. 5 2. New land supplies by means of drainage and irrigation. f 3. Abuse of agricultural land. 5 4. Means of restoring lost fertility. 5. Land for products other than food. 8. Destruction of the natural forests. f 7. Rapid consumption of coal. 8. Disappearance of mineral stores. f 9. Civilization's consumption of earth's stores. f 10. Land as a site for residence, commerce, and manu facture. f 11. Production of usable land surface in cities. 5 12. Dura tive character of hydraulic power sites. f 13. Goods varying in in creasableness.
§ I. Changes in the land supply. The greatest dynamic movements in industry of modern times have been caused by rapid changes in "the land supply," that great complex of area, fertile soil, timber, mineral resources, etc. This seems paradoxical, for "land," "nature," seems to be the one thing (or great group of things) which is fixed in amount. But the economic supply is that which is available in a mar ket. Land in Venus or Mars is of no economic importance to us, but lands on the earth as yet undiscovered or unavailable are a potential supply that, under certain conditions of price and of technic, may be realized.
The discovery of new trade-routes and of new continents in the fifteenth century had immediate economic effects upon Europe, but these began to be more largely felt as actual set tlement on these sparsely settled lands progressed in the seven teenth and eighteenth centuries. Pioneers from the most ad vanced peoples in the world moved on to take up these areas occupied only by small hunting tribes, and to use them by modern agricultural methods. They overcame the first great 442 difficulty of distance, dread, and mystery; they faced and overcame the danger from savages and wild beasts; they cleared the forest, opened paths and highways, and enlarged the supplies of new and fertile lands. They made these lands available to help supply many of the needs of the older countries, just as if the areas of Europe had been in creased.
The greatest change came in the middle of the nineteenth century with the use of steamships and the rapid building of railroads in the western states of America. This had an effect upon England and western Europe identical in nature with that which would have been produced had an area touch ing Europe risen out of the ocean. Every country in Europe has repeatedly felt the shock of these great economic changes which have lowered the price of nearly all kinds of their landed wealth. Because of increasing population (about 1860-1890) the need of land-uses was increasing very rapidly, but the supply of land-uses increased so much more rapidly that it caused the lowering of the value of the older lands in the eastern states of America and throughout Europe, the entire abandonment of some lands for agricultural purposes, and the neglect to repair and maintain a large part of the remainder.
The rate of this movement was more rapid in the nineteenth century than it ever had been, and perhaps more rapid than it will be again ; but in some measure such developments will continue for a long period. The land in America for cen turies was not, but now has become, for some purposes, a part of the supply in the same market as the land of England. The land in Greenland is not, and probably never can be, an important part of the supply of land in the world ; but the tropical lands will doubtless contribute increasingly to the supplies of food and materials used in the temperate zones.
§ 2. New land supplies by means of drainage and irriga tion. The habitable globe has now been fully explored and there are no more agricultural lands to discover. There are, however, great areas almost unusable in their natural states that can be made to blossom if properly improved. The greatest possibilities of this kind are in drainage and in irri gation. The improvements consist in insuring just that amount of water needed for cultivated crops.