NOTES OX JAPANESE EARTHQUAKES. 435 



28. Earthquakes in Yedo {Tokyo). In Yedo (Tokyo) there 

 have been since the 17th centnry 12 destructive earthquakes 

 whose time distribution is illustrated in fig. 18. They were most 

 frequent in the first half of the 17th century, when there were 

 seven in the interval of 34 years and 3 months between the 

 26th June IGL"), and the 1st September 1649, the mean inter- 

 val between two successive shocks being 4 years and 11 months. 

 Especially in 1649, there were two destructive earthquakes. 

 On the other hand, there was not one destructive earthquake in 

 the interval of 79 years between the 31st December 1703 and 

 the 23rd August 1782. 



In the course of the 240 years between the 1st September 

 1649 and the 2()tli June 1894, there were in Yedo (Tokyo) five 

 destructive earthquakes, the mean interval being 49 years. If 

 we simply count all the destructive earthquakes since the 17th 

 century, the average interval becomes 2") years. 



29. For the sake of reference I give in Table XXII 1 the 

 yearly earthquake numbers in Tokyo during the 23 years between 

 1876 and 1898. 



