EARTHQUAKE MEASUREMENTS TX PIT AND OX SURFACE. 



^29.)— April 11th, 1890.— A siualJ earthquake. 



281 



(^30.)— A])ril 18th, 1889.— A very Hinal] earthquake. 



Summary of Results. 



It is .generally heUeved that the earthquake motion is considerahly 

 less m a pit tlian on tlie surface. From the fore,<?<^ing calculati.^ns it 

 .seems prohahle that this is true for some earthquakes and not true f.n- 

 .^tliers. Among the thirty earthquakes we examined, there are three 

 which were especially severe. These are (1), (13), and (IS). The 

 rest are small earthquakes of the kind that daily occur in Japan. 

 The ratios of the amplitudes, periods, maximum velocities and 



