greater than the entire population of Britain. The total British coal production at present—290,000,000 tons yearly—consequently represents a working capacity more than ten times that of the whole population in terms of men, while the annual export of coal from Britain is equal to the emigration of ten million laborers.
Every horse power of available mechanical energy, therefore, should be estimated, not simply as a form of power permitting the use of appliances and processes which neither human nor animal energy could make available, but also as so many added members of the population which do not make any increased demands on the soil for food and the materials of clothing or shelter. The possession of this resource in abundance has, in the past, permitted nations to develop at a rate, or to an extent, which bore no relation to their ability to supply locally the necessities of life: the development instead being on a basis of exchanging the products of their mechanical power for the materials of food and clothing. This existence on a basis of exchange, however, involves the operation of two fundamental conditions. First, the important utilization of power does not appear until national development has passed beyond the stage of scanty population, hence it is logically one of the later stages of evolution. Second, the exchange depends on the existence of other national areas still in the early stages of evolution, not taxing their opportunities to their full capacity, and consequently capable of yielding a surplus of the fundamental necessities of life.
Such excessive development through the operation of one physical factor which temporarily overtops all others, as has resulted from the use of coal in Germany, for example, however strong the nation may appear at the time, is not a safe measure of the true strength and permanence of the nation. It may subsequently be greatly reduced by the natural changing of conditions, for unless the nation possesses in itself some ready substitute for coal when its supply is exhausted, as it inevitably will be exhausted comparatively soon for most nations, that nation must look forward to a future in which there are likely to be necessary certain sharp readjustments, with respect to its ability to take care of its own people. Moreover, as the nations now producing a surplus of necessities continue to advance in their own evolution and trend toward the maximum of their own capacity to feed, clothe and shelter a population, other readjustments, of perhaps even more sweeping character, may be necessary in those places where extensive growth has been based primarily on the means of generating mechanical energy. The stage wherein national importance in industry, commerce and population is derived from resources of coal is in any case transitory, and represents only one step in the gradual adjustment of all nations to their physical surroundings.
Water power in abundance, on the contrary, may be regarded as an