ON SEISMOLOGICAL INVESTIGATION. 



171 



The following observations have been received from Professor Dr. 

 Eschenhagen, Konigliches Meteorologisch-Magnetisches Observatorium, 

 Potsdam : — 



Becords of Magnetographs. 



Observations with a Conical Pendulum carryivg a small Mirror on a Glass Boom 

 20 cm. in length, and held horizontally by a Quartz Fibre. Period, about 15s. 

 The apparatus is similar to that iised for several years in Japan.^ 



The lists, it will be observed, are only comparable from January, 1897, 

 after which there are two magnetograph disturbances, corresponding to 

 two movements of the horizontal pendulum. The comparison between 

 these shows considerable dift'erences in time, and indicates the necessity 



' See Report of British Association, 1892. 



