DETERMINATION OF EARTHQUAKE ORIGINS. 191 



II. is the boundary of a shock confined to the plain 

 which surrounds Kofu. These earthquakes are evidently 

 quite local. Many of the disturbances have evidently 

 originated beneath the ocean, having come in upon the 

 land in the direction of the arrows A or B. 



III. This line indicates the boundary of a group of 

 shocks which are often experienced in Tokio. These may 

 come in the directions D, E, or f. It is probable that 

 some of them originate to the eastward of Yokohama, on 

 or near to the opposite peninsula. 



TV. Y. and YI. The earthquakes bounded by these 

 lines probably originate in the directions C or D. 



YII. The earthquakes bounded by this line probably 

 come from the direction E. 



YIII. This line gives us the boundary of earthquakes 

 which may come from the direction B. 



The above boundaries sometimes do not extend so far 

 to the westward as they are shown. At other times, 

 groups like Y. and YI. extend farther to the south-west. 

 These earthquake boundaries, which so clearly show the 

 effects of high mountains in preventing the extension of 

 motion, have been drawn up, not from single earthquakes, 

 but from a large series of earthquakes which have been 

 plotted upon blank maps, and are now bound together to 

 form an atlas. To give an idea of the material upon 

 which I have been working, I may state that between 

 March 1 and March 10, 1882,1 received records of no less 

 than thirty-four distinct shocks felt in districts between 

 Hakodate and Tokio, and for each of these it is quite 

 possible to draw a map. In addition to the boundaries of 

 disturbances given in the accompanying map, other bound 

 aries might be drawn for shocks which were more local in 

 their character. The groups which contained the greatest 

 number of shocks are III., lY., Y., YI., and YIT. By 



