A Magnetic Survey of Japan Reduced to 

 1895.0 and Sea Level. 



§ 1. Object of the Survey. 



The object of the survey was to get a closer view of the 

 distribution of magnetic force in the country than liitherto has 

 been done. It is hoped that we may obtain in this way some 

 insight into the tectonic character of the country which might 

 throw light upon the distribution of earthquake disturbances with 

 regard to time and space. 



The object w^as twofold, Hrst to obtain a general or normal, 

 as it is sometimes called, distribution and second to get the 

 extent and nature of local disturbances in special districts. With 

 the first point in view a comparatively large number of stations 

 were taken in places which were apparently free from distur- 

 bances of any great magnitude ; and with the second point in 

 view observations were made in volcanic regions or in places 

 where violent geological changes are supposed to have taken 

 place. How near we have come to realize those expectations is 

 cleai-ly shown in the maps. It will be seen that we have done 

 something toward the first, but for the second a much more 

 extended series of observations are needed, although we believe 

 that some of the prominent points are brought out by the 

 present survey. 



