248 



REPORT — 1898. 



Extract kkom the 'Bollettino della Societa Sismologica Italiana,* 



1895-7 — CO iitinued. 



No. 



17 



18 



19 



20 



O m ! 

 tn o * 



Earthquake 



gM^j Month Day Hour 



xr. 



Place of 

 Observation 



4 53 A.M. 



23 I 11 52 P.M. 



10 



5 7 A..M. 



10 43 A.M. 



1897 



Shide 



Potsdam 



Rome 



Shide 



Magnetograph Disturbances 



Wilhelmshaven. D and H = 0. 



V, 5h. 3m. to 5h. 12m. 

 Potsdam. D, 5h. 4m. to 51i. 



20m. n, 5h. 5m. Y, 5h. 



7m. (?). 

 Utrecht = 0. 

 Wilhelmshaven. D, 3m. to 4m. 



H = 0. V, 11 h. 58m. to 



17m. 

 Potsdam. D, 4m. to 14m. H, 



9m. to 13m. V (?) 

 Utrecht = 0. 

 Wilhelmshaven. D, 5h. 27m. 



to 5h. 28m. V, 5h. 22m. to 



5h. 38m. 

 Potsdam. D, 5h. 21m. to 5h. 



41m. n, 5h. 50m. to 5h. 



35m. V, 5h. 2Gm. to. 5h. 



35m. 

 Utrecht. D, 5h. 30m. to oh. 



4(5m. H, 5h. 27m. to 5h. 



53m. 

 Wilhelmshaven, Potsdam, 



Utrecht = 0. 



Utrecht = 0. 



Potsdam. ' V, <ih. 41 ra. to 9h. 



44m. Amplitude 1'. 

 Utrecht = 0. 



Until magnetograpli records have been obtained from other observa- 

 tories, and until .special experiments have been made, a.s, for example, to 

 determine the effect of artificially produced earthquake-like motion upon 

 magnetic needle.« and the effect of actual earthquakes upon non-magnetic 

 bars so suspended that their periodic movements are identical with those 

 of magnetic needles upon the same supporting pier, we cannot say with 

 certainty whether earthquake waves are or are not accompanied by 

 magnetic waves. 



In discussing the records brought together, which refer to the move- 

 ments of magnetic needles at tlie time of earthquakes, it is important to 

 consider the mechanical movements which occurred at the time of their 

 production. 



When a great earthquake has originated, as, for example, in Japan, 

 seismographic records indicate that about 16 mins. later Europe has 

 been swept with a flood of motion, and it might be imagined that one 

 observatory has practically been subjected to as much movement as any 

 other. 



