174 



A. TAXAKADATE AND H. XAGAOKA. 



iiig the general c("<in'8e of isomngnetics about those regions. And 

 tliis was all tliat we could do during the three weeks of winter 

 vacation whicli we had to spare. 



From tlie mean values at the stations, the intermediate values 

 were interpolated graphically, Ijy assuming tlie proportionality^ of 

 the space varip.tion of the elements Ijetween two stations, taking 

 care to interpolate across the isomagnetics as much as possible. 

 For tlie h(n-izontal intensity and declination, as well as for the total 

 intensity of the ])revi<3us surve}^, the values obtained at Xagoya were 

 so much out of the way that we at once perceived a local disturbance. 

 We therefore excluded Xagoya in the first interpolation, as it would 

 be wrong to assume proportionality across the space between which 

 there is a maximum or minimum. When the isomao-netics are 

 drawn with this exclusion, the course of the curves throws much 

 light upon the nature of the local disturbance, ^vliich we indicate, 

 according to our conjecture, by dotted Hnes. 



We notice from these cliarts, that tlie general nature of the 

 change is to make the lines more uniform than they were before. 

 This is re]narkal)]y shown l)y the observations made in Xagoya 

 where the l<_)Cul disturbance is very much reduced. Of all the svstems 

 of isomagnetics, the change for the equal horizontal intensity is the 

 most striking. r)y the old survey these lines were considerably 

 deflected from their o'cneral course, f;)rmino- a kind of ridae alorjir 

 the Mino-Owari plane up to the north c<3ast (^f Japan, l^y the 

 new survey they are made more uniform, still converging towards 

 the Wakasa Sea, beyond whicli the above named ridge might be 

 carried. 



xVnother remarkable point is tliat there was a minimum of total 

 intensity about Xag03^a, which now, Ijy tlie new survey, causes only a 

 small bend in the line of equal total intensity that passes very near the 



