EARTHQUAKE MOTION TO GREAT DISTANCES. 



163 



mentioned, of records of individual instruments which were markedly divergent from 

 those of others whose times were in close concordance with each other. To have 

 included these in the general average would not have led to greater, but to less, 

 accuracy in the result. 



As, moreover, the light horizontal pendula do not seem to respond with the same 

 consistency to the motion of the first two phases, as the heavily weighted pendula 

 user! in Italy, their records have l>een distinguished on the plate, being indicated by a 



7 



>*,' 



bOtr 



SOtn. 



10 m. 



jo" -ur sir r AT ea" air xr HP IKS' oo 

 Time curves of the three phases of earthquake motion recognisable in distant records. 



cross, while the records of the Italian instruments are plotted as circles. A small 

 figure against either cross or dot means that it is the average of a corresponding 

 number of not very divergent instrumental records ; where no figure is entered only 

 ;i single instrumental record is indicated. 



In the case of the third phase there was no reason for distinguishing between the 

 records of the two types of instruments, but by far the preponderating number of 

 records have been obtained from the Italian instruments. Generally when a light 

 pendulum with photographic record is affected by one of the first two phases, the 

 movement of the pendulum is so great in the third phase that the swing of the spot 



Y 2 



