TIMES AND PLACES OF EARTHQUAKES 539 



Africa as the stalk end. This point can not, however, be dealt with 

 here. The important thing is that there seems to be a real reason for 

 the occurrence of earthquakes in these particular regions, and that they 

 will probably continue to occur there. Professor Jeans's conclusions 

 have recently been examined by Lord Eayleigh, who announced at the 

 Royal Society only a few weeks ago that he found them generally con- 

 firmed, and that we must regard our earth as at present in a state far 

 from stable. 



The lessons to be learnt from the distribution of earthquakes in 

 space are accordingly tolerably plain in theory, though in practise we 

 may not be able to take advantage of them. If we would be partic- 

 ularly safe from earthquakes, we must take up our abode near one of 

 the ends of the pear — either in Africa or in the Pacific. There is 

 also a region of safety between the two dangerous rings — in America 

 generally, for instance, excluding the west, or in Siberia. But the 

 dangerous regions include so vast and so valuable a part of the earth's 

 surface that it is impracticable to leave them unoccupied. Moreover, 

 our knowledge is as yet not specific enough. In the dangerous regions 

 themselves, some parts are much more dangerous than others; for in- 

 stance, Japan, which is reckoned above as a single region, can be 

 divided into at least fifteen distinct seismic districts. As observations 

 are accumulated we may be able to make similar partitions of the other 

 regions. For the present the general attitude towards earthquakes 

 will probably be similar to that towards other dangers, such as those 

 of travels and voyages for instance; the risks must be incurred. We 

 know that there are at times fatal tornadoes; but other interests are 

 at stake, and we put to sea in the hope that none will occur during our 

 voyage. 



We come to the second point, the distribution of earthquakes in 

 time. Are there seasons of special activity such as the recent occur- 

 rence of several disasters seems to suggest? Here our knowledge is 

 slighter still, and the observed facts have not yet been coordinated by 

 a mathematical investigation. Still there seems to be some evidence 

 in support of the view that exceptional irregularities in the rotation of 

 our earth may be responsible for an increased number of earthquakes 

 at particular times. That the evidence is slight must be attributed 

 to the shortness of the time during which it has been possible to obtain 

 it, and not necessarily to inherent weakness in the evidence itself. The 

 brevity of the earthquake record has been mentioned above; that of 

 irregularities in the earth's rotation is longer; but the discovery that 

 such irregularities existed was made only twenty years ago, though 

 the phenomenon was then traced back through the old observations. 

 The irregularities are systematic in character, and the law governing 



