EARTHQUAKE MEASUREMENTS OP RECENT YEARS. "5 



alj aziinutUs during a prolong-ed .-iliakiiig. Fn the earthquakes discussed 

 ill the present paper tlie direction and the distance of the <n-igin of 

 (b'sturbance from the observing station were known, as also the 

 <lirection of tlie maximum movement of the ground. Xo definite 

 relation l)etweeH these du-ections can Ijc established. Seismic waves 

 indeed must sutler much reÜection, refraction and diffusion as they 

 nrooTess, and the co-existence of normal and transverse waves is a 



1 O ' 



distinct element of confusion. 



Out of 119 earthc|uakes recorded in the tables 42 were local 

 shocks, which extended only over a small tract of land from a few 

 miles to 10 or 15 miles around. They caused the ground only 

 slightly to tremble and the horizontal motion of the ground was 

 from 0*1 m.m. to O'o m.m., or even less. There were four cases 

 in which the nitjtion reached 0.8 m.m. Xo vertical motion occurred 

 in these local shocks. 



There Avere 119 shocks during the two years, which means more 

 than one shaking ])er week. 



As the continuation of these observations will be published in 

 the coming»' numbers of this Journal further oreneralizations or conclu- 

 sions, that might be deduced from the facts now given, will be 

 reserved for a future paper. 



