i8o THE POPULAR SCIENCE MONTHLY 



40 per cent, of the total fall, the gross discharge through surface drain- 

 age per year from the entire area of Britain is equal only to about one 

 fifth the annual discharge of the Mississippi Eiver system. All of the 

 streams in Britain have the major part of their courses where the land 

 is well under an altitude of 1,000, an elevation less than that of most of 

 the Mississippi drainage basin. In the streams of the latter system the 

 available water power has been estimated to be as high as 25,000,000 

 horse power. Calculated on the same basis, and in terms of their total 

 discharge, the maximum power capacity of the British streams would 

 not exceed 5,000,000 horse power, which, even if increased by 50 per 

 cent., to give a generous estimate because of the shorter and more rapid 

 descent of some of the British streams, falls far short of meeting the 

 present British needs for mechanical energy. Hence, the dependence of 

 Britain on her streams for power would mean not merely the inability to 

 take care of an increasing population, but also an actual lessening of her 

 ability to support, as at present, the numbers already existing. 



This amount of power from streams, however, might be materially 

 supplemented by the utilization of energy in the rise and fall of the 

 ocean waters in the tides, the feasibility of which, under favorable con- 

 ditions, has already been demonstrated at different places along the 

 coast of this country. Here once more the position of Britain, its size 

 and configuration, are decidedly favorable for the development and 

 general use of such wave and tidal power; practically every locality in 

 the kingdom being so situated as to be able to benefit from its use under 

 the present condition of transmission of power over wires in the form 

 of electricity. Estimates of the extent to which energy of the tides can 

 be utilized for commercial purposes are still largely conjecture, since 

 the need for turning to that source of power has not yet risen, but it 

 eeems not unlikely that the future of Britain is to depend, perhaps more 

 closely than ever, on those same physical factors which have been so 

 significant in practically every chapter in the past — her insular position, 

 compactness and configuration of the coast. 



Germany, on the other hand, confronted by the same problem of 

 coal exhaustion, has a less hopeful outlook because of her different 

 surroundings. Germany with a large and rapidly increasing popula- 

 tion, already grown well beyond the food capacity of the national area, 

 recognizes the necessity for providing for her increasing numbers by 

 increasing commercial and industrial activity — all dependent on 

 mechanical energy. In this respect Germany is less favored than 

 Britain, not only as regards coal, 2 but also as regards water power to 

 replace coal. Calculated on the basis of an average rainfall of 30 inches 

 and a run-off of 40 per cent., both of which figures are high, the total 

 2 The actual quantity is estimated to be a little larger in Germany, but so 

 much of it is lignite that it has distinctly less industrial value. 



