MAGNETIC SURVEY OF JAPAN FOR THE EPOCH 1895.0. 169 



ai^reeins: much closer with the observed values, althou2;h it 

 reduces the residual field at the epicenter to about one-fifth of 

 the previous value. 



Treating similarly the variational anomalies in Europe given 

 in Tables XXIII and XXV, we observe that the arcs from the 

 five points in Austria and Hungary converge very nearly to the 

 south west of Norway, while those from the stations in Great 

 Britain converge towards the south east of Greenland, except the 

 arc from the Station IX which intersects three of the arcs in 

 south of England. This last discrepancy would seem to be due 

 to local anomaly of the west component in the district, as is seen 

 from Map 9 of the report of that survey, by a large number of 

 stations in this district having disturbance tow^ard the west 

 compensated by a few stations in north of Wales ; namely, out of 85 

 disturbances 53 are positive and 32 negative. The azimuth from the 

 station IX is hence omitted. ^^y 14 



Since those variational 

 anomalies are affected by 

 various disturbances of small 

 extent as well as errors in the 

 expressions of mean isoraag- 

 netics, we take for the first 

 trial, one image at the mean 

 point of intersections of the 

 four British arcs and five 

 Austro-Hungarian arcs, in- 

 stead of two distinct images. 

 This point comes out : — 



Longitude 9.°0 W. Latitude 65.°1 N. 



The vertical variation of the vertical force — g— , is negative 



