1906.] 



SEE— THE CAUSE OF EARTHQUAKES. 



309 



Imagine a mountain chain like the Andes which runs near the 

 shore cut up into pieces each long enough to reach the sea. If 

 there is no physical cause why the chain should be parallel to the 

 seashore, some of the pieces might be expected to lie at all angles 

 with respect to the shore line of the coast from 0° to 90°, and thus 

 the chain's most probable form is that of a zig-zag line made up of 



Fig. 6. 



I SOUTH AMERICA 



I SCALE 



s 



short pieces lying at all angles. Take the intervals of angular dis- 

 tribution of the pieces of the chain at 9° ; then, excluding the exis- 

 tence of physical causes, any angle from the first interval, 0° to 9°, 

 to^the last of these subdivisions, 81° to 90°, must be held to be 

 equally probable. At any place there are ten divisions of the quad- 

 rant, all equally available for the mountain chain to follow. The 



