ON SEISMOLOGICAL INVESTIGATION. 



67 



grams obtained in Edinburgh, Shide, Leghorn, Eocca di Papa, and 

 Catania there are excrescences succeeding the maxima movements at 



Fig. 1. 



70 ZO 30 40 60 €0 70 60 dO JOO IW 7W 130 ?40 JSO 360 770 MO 



m 



90 



60 



70 



60 



SO 



OC 



ZO 



W 



io ZO 30 tw 60 60 70 60 90 too ijo /ZO lao iw 160 160 170 m 



Arcual Velocities. — la. Preliminary Tremors by direct observatiou ; lb. Preliminary Tremors 

 deduced from Ila ami III ; Ila. Largo Waves if tlie Velocity is constant ; lib. Large 

 Waves if the Velocity varies ; III. Intervals by which Preliminary Tremors outrace Large 

 Waves. 



times we should expect them to occur on the supposition that they had 

 travelled round the world from their origins on the longest paths. 



"Without discussing the merits of the particular seismograms here 

 referred to, we must bear in mind that it is possible for body waves to 

 give rise to repetitions by reflection just as easily as two trains of waves 



p3 



