94 EARTHQUAKES. 



correct and rate the clocks from which the observations 

 were obtained, thej may be regarded as being tolerably 

 correct. 



The disturbance of February 6, the two shocks of 

 March 1, appear, like that of October 25, to have passed in 

 almost a direct line from an origin in the N.N.E. through 

 Tokio on to Yokohama. Their velocities of propagation 

 as calculated from the above intervals are approximately 

 3,900, 1,900, and 1,400 feet per second. The shock of 

 February 1 6 appears to have had its origin near to a point 

 in Yedo Bay about eight miles east of Yokohama. 

 Assuming this to be the case, the shock between the 

 Yokohama homoseist and Tokio travelled at the rate of 

 2,454 feet per second, but between the Tokio homoseist and 

 Chiba at the rate of 750 feet per second ; that is to say, the 

 velocity of propagation rapidly decreased as the disturbance 

 spread outwards. 



At Yokohama it was recorded at 5.31.54, at Tokio at 

 5.32.16, and at Chiba at 5.33.48. These times are given 

 in Tokio mean time. 



The shock of March 1 1 , which was recorded at Tokio 

 at 7.51.22 P.M. and at Yokohama at 7.51 .33 P.M., appears, 

 from the indications of instruments w^hich were exception- 

 ally definite in their records, to have originated in the N.E. 

 corner of Yedo Bay, about nineteen miles S.S.W. from 

 Chiba. This shock was rather severe, fracturing several 

 chimneys. From the Tokio homoseist it appears to have 

 travelled on to Yokohama at the rate of about 2,200 feet 

 per second. Assuming these observations to be approxi- 

 mately accurate, if we take them with the records of 

 previous observers they lead us to the following conclu- 

 sions : — 



1. Different earthquakes, although they may travel 

 across the same country, have very variable velocities. 



