236 WORLD-POWER AND EVOLUTION 



Among these four it is difficult to decide which is the best. As 

 may be seen from the lowest line they present a series in which 

 the contrast between summer and winter becomes progressively 

 greater. So far as mean temperature is concerned, London 

 appears to be the most favored, although its difference from Paris 

 is negligible. In both places the January average is close to the 

 temperature which is best for mental activity (40°), while the 

 July average almost coincides with the optimum for physical 

 activity (64°). The fact that London is damper than Paris 

 probably makes its climate a little the better of the two, for we 

 have seen that in spite of our prepossessions a damp climate is 

 better than a dry one, provided it is not too hot. Berlin is too 

 cold in winter, but of just the right temperature in summer. New 

 York is not only too cold in winter, but too hot in summer. So 

 far as mean temperature and humidity are concerned, it seems 

 probable that the cities are arranged in order of excellence, 

 London being first and New York last. 



It is not enough to look only at temperature and humidity. 

 Changes of temperature are equally important. Viewed from 

 this standpoint the order of the four cities is reversed. New York 

 easily stands at the head, while London is least favored. As yet 

 our investigations have not gone far enough to enable us to bal- 

 ance the advantages of the one against the other. If I were 

 obliged to express an opinion in the light of present knowledge 

 I should have to confess that Berlin may have a very slight 

 advantage over any of the others. At any rate there is no deny- 

 ing the fact that Germany is today blessed with as fine a climate 

 as any in the world. How far this accounts for her tireless energy 

 and her ceaseless preparations I dare not attempt to say. That 

 it is an important factor seems almost certain. 



Before we discuss this matter further let us see how many 

 people actually live in highly stimulating climates. Here again, 

 we must proceed with great caution, for we are only on the 

 threshold of this subject. The figures that I shall give are based 



