THE DISTRIBUTION AND PROBLEMS OF POWER The Sources of Power.—The chief sources of power are coal, moving water, petroleum, animals, wood, wind, and natural gas. To begin with the least important, natural gas and wind are used only locally and their use tends to decline. In backward regions wood is still the main source of heat for domestic purposes and an important source of power for manufacturing and transportation. In more advanced regions its great value for other purposes has almost put an end to its use to generate power for manufacturing. In spite of the great increase in gasoline engines and tractors, animals are still the main source of power for transportation on farms even in progressive countries and for all sorts of transportation away from railroads in backward countries. Their use, however, belongs primarily to agriculture. At the time petroleum, especially in the form of gasoline, or petrol, as the English call it, takes high rank as a source of power. Nevertheless, in 1922 it furnished only about 3 per cent of the power used industrially in the United States, and its importance dates back only to the beginning ofl the present, century when explosion engines first became common. Moreover, according to the geological experts, the supplies are being exhausted so rapidly that within a generation the role of petroleum as a source of power may once more be insignificant. Nevertheless, it will leave behind it the legacy of the light, high-powered explosion engine which has been the main factor in the development of both the auto mobile and the airplane.
This leaves water and coal as the two main sources of power. The Romans are said to haVe been the first to apply water power to flour mills. The Domesday Book shows that England was full of water mills at the time of William the Conquerer, about 1066, the number being some five hundred in Norfolk and Suffolk alone. In 1920 water furnished' about nine million of the horse power used in the United States, while coal supplied 33 million, and gas and oil one million. These figures do not!
include locomotives and automobiles. In the future the use of water power will probably increase rapidly, for among the sources of power now commonly in use water is the one whose supply is least in danger of exhaustion.
The Relation of Power to Progress.—Although the steam engine as used somewhat before 1800, it was not employed extensively until he early part of the nineteenth century. Since then steam power has • fluenced modern industry and transportation so profoundly that many people have supposed that coal, the chief source of power, is actually the cause of manufacturing and that manufacturing is the primary cause of progress in civilization. This mistake should be carefully guarded against. The power derived from coal did not cause , England, for example, to become a leader in manufacturing and com merce. Before the invention of the steam engine England was already the world's leader in both respects. English cutlery, made by hand, was famous in many countries. English cloth, likewise made by hand, was also widely known; and English tools and machines were the best to be had. At the same time English ships were sailing to all parts of the world, and then as now were the most noteworthy carriers of com merce. Next to England in these respects came the neighboring countries bordering the North Sea, including Belgium, France, the Netherlands and Germany. Switzerland, too, was famous for its fine clocks and watches, its cotton cloth, and its silks, just as today. In the New World before the time of the steam engine, New England was the chief manufacturing center•; cotton from the South was shipped to that section and the finished product shipped back again much as at present. Commerce, too, was active from Boston to Balti more, and languished farther south. In short, except for almost uninhabited regions to which Europeans have since migrated—for example, the United States west of the Appalachians—the general centers of industry and commerce were then almost the same as now.