DISTRIBUTION OF EARTHQUAKES IN TIME. 239 



command, are not to be confuted. If, however, instead 

 of considering the seismic energy of the whole world, we 

 consider the seismic energy of particular areas, it seems 

 reasonable to expect that in certain instances sometimes 

 a decrease and sometimes an increase in this energy 

 might be discovered, especially, perhaps, in areas which 

 are highly volcanic. 



In France we know that volcanic activity ceased at a 

 period closely bordering on historical times, and it is not 

 unlikely that seismic activity may have ceased at a corre- 

 sponding time. 



In a country like Japan, it is possible that in one 

 district seismic energy may be on the increase, whilst in 

 another upon the decrease. 



In a country like England, it is probable that the 

 seismic state is constant, and, whatever changes may be 

 now occurring, they are taking place at so slow a rate 

 that, even if our records of the historical period were 

 complete, we could hardly be expected to find these 

 changes sufficiently marked to be observable. 



For purposes of reference, and also for examining the 

 present question, the table, page 240, has been compiled. 

 The earthquakes given are chiefly those which have been 

 recorded in histories as being more or less destructive. 



In the second column of this table will be seen the 

 number of earthquakes which have occurred in Japan 

 during each century, the centuries being marked in the 

 first column. In columns 3 to 18 inclusive are given the 

 number of earthquakes which have occurred during dif- 

 ferent centuries in the various countries and districts 

 mentioned at the head of each column. These latter, 

 which are taken from the writings of Mallet, are given 

 for the sake of comparison with the Japanese earthquakes. 

 If we commence with the seventh century in the column 



