36 



ART. 6.-S. KUSAKABE 



The values of - given in the second row correspond to the case 



where one may be neglected as compared with — j while those in the 



last row correspond to the case where the waves propagate through an 

 infinitely extended uniform stratum of marble. The last is calculated 

 using a value of Jc determined experimentally, the result being traced 

 in Fig. 38, PL XVIII. 



Quite independently of the above hysteresis function, the ratio of 

 velocities of several waves through a stratum of serpentine and pyro- 

 xenite are obtained from the experiments shown in Pis. IV„. and IV,,. 



Table V. 



1 1ère we can not omit to remark that, though the values given in 

 Table IV. may be absurd as it stands on the foundation of the 

 hysteresis function, those in Table Y. can not be disputed by any 

 one even with the result of the most subtle, analysis, provided that 

 the foundamental formula, which expresses that the velocity varies 

 as the square root of the rigidity-modulus of the medium through 

 which the wave propagates, be granted. 



By the equation (25), it can not be disregarded that the velocity 

 of propagation increases when the stratum of rock, through which 

 the wave propagates, is in a strained state. Thus, for example, the 

 seismic wave would probably propagate more quickly along a 

 mountain chain than in uniform plain land. ' This variation, how- 

 ever, is much smaller than the former. 



From what has been above discussed, it may safely be said that 



