The result of these various influences is far-reaching. Because of the long summer days and short nights, wheat can be cultivated to the sixtieth parallel. Corn, which gets scarcely enough warmth and light in the torrid zone to become a prolific crop, attains its greatest yield in the latitude of fourteen-hour days. These factors, it is evident, carry the grain and meat industries into regions that otherwise would not be habitable. Because the long summer days produce these great food-crops, commerce and its allied industries have reached their maximum development in these regions. Human activities are greatest in the zones bounded by the thirty-fifth and fifty-fifth parallels, the zone that includes the greater parts of the United States, Europe, China, Japan. They are greatest, moreover, because of their geographical position. QUESTIONS FOR DISCUSSION What would be the probable effect on the food-crops of the United States were the main body of the country moved twenty degrees north in latitude? Which would then be the wheat-growing States, the cotton-producing States? Illustrate the connection between occupation and altitude above sea-level. What difference would it make to the corn-crop were the days and nights always twelve hours long? What would be requisite to make Canada a centre of silk production? Why is not cod-fishing an industry off the east coast of Florida? Why is the greater part of the Russian Empire destined to be sparsely peopled? FOR COLLATERAL REFERENCE A rain chart of the world. A chart of isothermal lines. CHAPTER V TRANSPORTATION--OCEAN AND INLAND NAVIGATION Of all the adjustments which come into the lives of a people none has been so far-reaching as the gradual localization of industries each in the region best adapted to it. For instance, manufacturing industries require power, but not fertile soil; therefore the manufacturing industries seek nearness to fuel or to water-power, and a position available for quick transportation. Farming does not require any great amount of natural power; on the contrary, level land having a great depth of fertile soil is the essential feature. The farmer must therefore look first of all to conditions of topography and climate, and secondly to the means of transporting his crop. Mining cannot be an industry in regions destitute of minerals; the miner must therefore go where the mineral wealth is found, without regard to climate, soil, centres of population, or topography. But two things are required--the mineral products and the means of getting them to the people--that is, ready means of transportation.