198 KNOTT AND TANAKADATR 



nve respectively Kôfii and Hakone, stations wliicli He in what is one 

 OÏ the most distiirhed regions in Japan. Hakone indeed is quite pe- 

 culiar magnetically, and is included amongst the 81 stations more as 

 n curiosity than otherwise. It is situated in a hilly and highly vol- 

 canic reofion on the shores of a deep tarn-like lake. A small piece of 

 stone ]ncked up from the ground and hrought nenr the declination 

 magnet had a large eifect upon it. Neither Kôfu nor Hakone belong- 

 to the selected staticms. No. 73, liamada, near the extreme westerly 

 end of the country, does however belong to the selected stations. 

 It will be noticed that the contiguous station, No. 72, Hagi by name, 

 shows also a large difference between the observed and calculated va- 

 lues of the Dip, but that the difference is positive whereas the diffe- 

 rence in the case of No. 73 is negative. The same approximate bal- 

 ancing of differences exists also in the case of Köfu and Hakone. We 

 shall consider this point more in detnil subserpiently. 



If we take into account (^nly the Fifty selected stations, the pro- 

 bable error is ± 9 '.5 6. 



Four of the selected stations stand out prominently by virtue of 

 their large differences. These are Kashiwazaki ( No. 35 ), Hichiya- 

 mura (No. 68), Tlngi (No. 72) and Hamada (No. 73). If we ne- 

 glect these, the probable error becomes ± 6 '.96. Hichiyamura is 

 one of the Kyüshü group of stations (Nos. 65-71), all of Avhich lie 

 in a very volcanic region and all of which have their observed Dips 

 less than the corresiionding calculated Dips. 



It is worthy of note that the extreme Yez<^ staticuis, Kiitup an<l 

 Nenuuv^ (Nos. 18 and 19), fit in remarkal)ly well with the general 

 formula — better indeed than do the less extreme stations Hakodate 

 and Sapporo (Nos. 16 and 17). At Hakodate (which is one of the 

 Fifty) the proximity of Hakodate Peak, a hill of volcanic rock 1,100 

 feet high, might well be n source of disturbance. At Sapporo again, 



