The conclusion which we are therefore led to with regard to this shock, assuming of course that the time observations are tolerably correct, is that the velocity of propagation was variable, being greater when measured between points near to the origin than between points at a distance. The velocities estimated vary between 4,000 and 9,000 feet per second. In the case of the earthquake which has just been discussed, we have an example of a disturbance which must have passed between Tokio and Yokohama in what was almost a straight line from the origin. As this direction ought to give the maximum time of transit if all earthquakes are propagated with the same velocity, the following table is given of the interval between the time of observation of several shocks at these two stations:— FROM YOKOHAMA TO TOKIO. FROM TOKIO TO YOKOHAMA. 1880 December 20th 36 seconds | 1882 October 25th 21 seconds 1881 January 7th 14–31 „ | 1883 February 6th 23 „ „ March 8th 60 „ | „ March 1 53 „ „ „ 17th. 66 „ | „ „ „ 63 „ „ November 15th 31 „ | „ 8th 27 „ 1882 February 16th 22 „ | „ „ 11th 26 „ As these are observations which have been made with the assistance of a telegraphic signal daily employed to correct and rate the clocks from which the observations were obtained, they 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 16 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 11, 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 which were exceptionally 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 _approximately_ accurate, if we take them with the records of previous observers they lead us to the following conclusions:—