THE DIA.gr AM OF THE SEMI-DESTRUOTIYE EARTHQUAKE. 291 



and 4th soconds. This was followt'd hy a oounter-inovemont of 7o 

 mm., Avhich was tlie maxiimini Jiorizontal motion «hivinu" tlie earth- 

 ("(uake, and was a£:Tiin followed hy a motion of 42 mm. The m<jtion 

 during ahont 1 minute succeeding tlie ahove three most prominent 

 shocks was verv mucii -weaker, though still great in range. Some 

 large undulations ocrau'red hetween the 40ih and nDvd seconds and 

 again hetween the 7<)t]i aiid 78th seconds. Ihit the intensity of 

 motion was not so strong as hefore. The com])arativelv little damage 

 occasioned hv the prescrit earthquake notwitlist;uiding such great hori- 

 zontal movements is no douht dn.e to tlie sin;!!! numl)er of violent 

 oscillations. 



reriod of rfnrl:())it<il Motion. 4"he rdi(Tve maximum liorizontal 

 motion was executed in 0-1) second, so that the complete period of 

 oscillation wouhl he InS second. 



Direction of Motion. 44io directif^n of tlie motion changed as usual 

 during the earthrpiake. Ihit the maximum horizontal motion was 

 directed toward S, 70'' W., and the chief movements l^efore and after 

 were also directed nearly towards the same point, or else the opposite 

 direction. We have also examined the directions of overturning of 

 2ir) stone-lanterns Çisliiilôrô') in different parts of Tokyo. Their mean 

 direction of overturning v\-as toward S. 71^ \V. 44ius the direction of 

 overturning of columns is seen to i)e identical with that of the maxi- 

 uHun liorizontal motion. 



1 ertical Mntion. The maximum vertical motion of 10 mm. 

 occurred in the 'îixl second nearly sinudtaneouslv with the iirst ])ro- 

 minent h(^rizontal niotion. AVrtical moti<uis o<:curred more or less 

 during the next ,')0 seconds. 



Maximum Actrl erat ion. The maxitmun acceleration of the motion 

 of an earth particle, calculated from the ahove values of the maximum 

 horizontal motion and its period, is 444 mm. per sec. per sec. 



