140 Reports & Proceedings — Geological Society of Lonaon. 



the load, and the prevailing direction of the horizoatal stress 

 between east and south, during the six hours before the meridian 

 passages at noon and midnight, and of an increase in the downward 

 pressure and a horizontal stress between south and west during the 

 next six hours. The record was accordingly grouped by the 

 successive two-hour periods from XII to XII o'clock, and the mean 

 amount of variation in the stresses was calculated for the same 

 periods. The result is set forth in the appended tabular statement: — 



Distribution op Stresses and Shocks in Two-Hour Periods, 

 before and after midday and midnight. 



From these figures it is seen that, while there is no apparent 

 relation between the frequency and the total, or the horizontal,, 

 stress, there is a close one with the variation of the vertical stress ; 

 the greatest number of earthquakes being in the period in which 

 there is the greatest increase of downvrard pressure; as the rate of 

 increase diminishes the number of shocks is less, suffering a further 

 diminution as the pressure begins to decrease, and reaching it& 

 minimum in the period where the decrease in pressure is greatest, 

 increasing again in the same way to the maximum. 



An attempt to apply the same method to the Japan record gave 

 a result which was, at first sight, contradictory and also inconsistent 

 in itself, for it gave an absolute maximum at the time when the 

 Italian gave a minimum, with another maximum, almost as great, 

 in coincidence with the Italian ; but, in any comparison, it is 

 necessary to allow for the contrast in the character of the two- 

 records. The Italian does not contain more than two, or at most 

 three, great earthquakes of the type that gives rise to long-distance 

 records (bathyseisms), and the aftershocks account for no more than 

 a quarter of the whole record; the Japanese record, on the other 

 hand, is dominated by bathyseisms and aftershocks. Not only does 

 the region give origin to an unusually large number of teleseisms, or 



