178 A. TANAKADATE. 



pulsions from the plateau or attractions towards the volcanic 

 range which runs parallel to it on the west side. 



Again the disturbance observed in Miyako, No. 176, looks so 

 singular among its neighbouring stations in having its direction 

 contrary to the rest, that some arithmetical mistake was suspected ; 

 a close examination into the notes shows no sucli blunder; turning 

 to the previous observations of Knott and Nagaoka, which were 

 made in a different part of the town across the river, even a 

 greater effect in the same sense is found. Whether this disturbance 

 is limited to the vicinity of the place, or extends along the coast, 

 must be found by further observations ; if the latter be the case, 

 there will be a ridge along the coast probably running partly in 

 the sea, and what is apparently a valley line in the middle of 

 the plateau may turn out to be nothing but a magnetic plane. 



The existence of such a ridge along the edge of a district of 

 older geological formation is suggested by the presence of a 

 similar line on the north coast of the granitic region of Tyügoku. 

 This ridge in Sanindö would seem as if to have continued with 

 that along the coast of Hokurikudö, had it not been obliterated 

 in the middle by the rupturous entrance of Wakasa Bay. 



Remarks similar to those apply to all the ridge and valley 

 lines marked on the map ; their details are scarcely worth men- 

 tioning, suffice it to say that they are no more than traits of the 

 writer's imagination. 



Ajjproximate lines of Force : — In the island of Sikoku and 

 Peninsula of Kisyû, the disturbing forces seem to be arranged 

 so systematically, that an attempt is made to draw approximate 

 lines of force by tracing their envelope in a rudimentary way. 

 (see Map 10). Though those lines appear to show a submarine 

 source of disturbance off the Pacific coast, our results are yet too 



