RIGIDITÏ OF BOCKS AM» HYSTERESIS FUNCTION. 37 



of several waves, the one whose amplitude is smaller has Qecessarily 

 a greater velocity than the other. WheD the yielding predominates, 

 the velocity may become two or three times .smaller as the amplitude 

 becomes some ten times greater. The disturbance of smallest ampli- 

 tude will first make its appearance as the beginning of the preliminary 

 tremor, followed by waves of greater amplitudes in succession. 

 Other disturbances, propagating through differenl strata or of other 

 origin, would probably appear intermixed with the former, giving a 

 somewhat irregular record on the seismograph. 



J 11 Table III., the velocities of propagation of transversal waxes 

 through several rocks are also added. They serve only to give a 

 general idea of the order of magnitude, since the velocity is never 

 constant for any specimen, as there exists more or less yielding. 



In conclusion, I wish to express my great indebtedness to Mr. 

 Fukuchi for valuable information concerning 1 the geological and 

 penological character of the specimens examined in the present experi- 

 ment. Mv best thanks, however, are due to Professor H. Nagaoka 

 and also to Professor A. Tanakadate, without whose valuable advice 

 and most kind guidance I could scarcely have succeeded in carrying 

 out this experiment. 



