8 s. Xakamura and K. Honda : 



station with only one well developed oscillation with a period of 

 15,4 minutes, Avhile Figs, h and c are curves at the Hakone station 

 with oscillations of 6, 7 and 4,4 minutes, respectively. Now Figs. 5 

 are curves obtained also at Hakone. On looking at them we can 

 discern distinctly the existence of the shorter 6,7 minutes period 

 probably accompanied by the longer oscillation of 15,4 minutes.' 



Fiff. 4 



In order to determine the exact values of the periods of oscil- 

 lations supposed to be present in a given curve, we made use of a 

 simple device. Four zinc strips about I cm. broad and 30 cm. long, 

 were hinged together at their ends so as to form a deformable paral- 

 lelogram. In each of the two opposite pieces, a series of equidistant 



