DISTEIBUTION IN SPACE AND TIME. 229 



Scotland, and the shakings which are occasionally felt in 

 countries like Egypt. The earthquakes which shake the 

 borders of the Pacific have their origins in, and their effects 

 are almost exclusively felt on, the sides of the bounding 

 ridge facing this ocean. In Japan it is the eastern sides 

 of the islands which suffer, the western side being almost 

 as free from these convulsions as England. 



Similar remarks may be made about the eastern side 

 of South America, especially the southern portion of the 

 continent. At Buenos Ayres, for example, there has been 

 no disturbance since Mendoza was destroyed, some twenty 

 years ago. In British Guiana slight shocks are occasion- 

 ally felt in the low delta which forms the settled portion 

 of the colony, but they are extremely rare. 



Disturbances in lines or zones. — It has often been 

 observed that disturbances are propagated along the length 

 of mountains or valleys, and it is but seldom that earth- 

 quakes cross them transversely. Thus the valleys of the 

 Rhone, the Rhine, and the Danube are lines along which 

 disturbances travel. 



The major axes of the elliptical areas of disturbances 

 which have shaken India have a general direction parallel 

 to the valley of the Granges along the flanks of the 

 Himalayas. 



The disturbances which have shaken London appear 

 to have been chiefly east and west, or along the valley of 

 the Thames. In South America the line of disturbance is 

 along the western sides of the Andes. Another line is 

 along the northern coast of the continent through Anda- 

 lusia and Caraccas towards the Antilles and Trinidad. The 

 shocks of the Pyrenees are chiefly felt along the southern 

 side of these mountains. In the middle and on the 

 northern side they are but seldom felt. This propagation 

 in lines or zones may in certain cases be apparent rather 



