MAGNETIC ÖUKVEY OF JAPAN FOK THE EPOCH 1895.0. 11 



18U3 



1894 



1895 



1896 



^ 5. Method of Observation. 



The Vibration Experiment \y;is always made [)efore the de- 

 llection experiment in determiniDg the horizontal intensity. This 

 was generally done by two men, an observer gave signal of the 

 transit of the reflected line in the ol)serving telescope by making 

 a tap with a small piece of wood, and a recorder looking at tlie 

 chronometer noted dow^i the time estimated to nearest tenth of a 

 second ; 15 successive transits in the same direction were observed 

 at the beginning and end of 50 complete vibrations, the chrono- 

 meter being placed at 11 meters distance from the magnetometer. 



When it was performed by a single person the eye and 

 ear method as in the case of star transit was employed ; this 

 I'ecpiires the period of magnet to be greater than four seconds. 

 A correction on account of the non-uniformity of the visible 

 jnotion is applied which is easily found to be 



* In 1893 the bar magnet No. 1 was used with tlie nitignetunieter No. 2 and the 

 reduction is carried accordingly. 



