302 T. Terada and T. Matuzawa 



scrutinized and elaborated by Tanakadate liiniself, by which the 

 reliability of the results obtained was ensured. Recently, N Wata- 

 nabe<^'^ succeeded in devising and constructing a very convenient form 

 of portable electric magnetometer. It enables us to make a set of 

 observations in a remarkably short interval of time, with a sufficient 

 accuracy for most purposes, and promises to be of great use in future 

 survey work. 



The abundant data afforded by these two general magnetic surveys 

 have, however, not yet been anah^sed and discussed in connexion with 

 the seismological points of view and remain reserved for future 

 investigators. 



As already mentioned, K. Shiratori observed in Sendai on the 

 occasion of the recent Kwanto Earthquake, an abruj)t cliange in the 

 potential difference between the two metallic electrodes driven into 

 the soil. Though a similar phenomenon had been early studied by 

 J. Milne^^^ and attributed to some change in the electrodes themselves, 

 yet a further investigation of the matter seems desirable. 



The measurement of the underground temperature has been under- 

 taken by the E.I.C. from the earliest dates, in wells and tunnel s."^"'^ 

 Later, K. Fuji"^^^ made observations on some deep borings in mines 

 and oil fields. No systematic general survey has, however, yet been 

 attempted. 



In this respect, K.Misawa's^^- recent investigation into the temperature 

 distribution in the hot spring district of Suwa, Province of Sinano, is 

 worth notice. The springs are arranged in zones in a characteristic 

 way, among which he remarked a regularity of temperature distribu- 

 tion connected with the tectonic structure of the district. 



Here, K. Honda and T. Terada's investigation into the geyser of 

 AtamijC'^ and K. Honda and T. tone's study of the geyser of Onikobe^'^ 

 may also be mentioned. 



(1) N.S.B.K., [iii] 2 (1920), 210; Jap. J. Astr. Geopliys., 1 (1924), 191. 



(2) Trans. Seism. Soc. -Tap., 15 (1890) 135; 19 (1894) 23. 



(3) Tanakadate, Ho.. 45 (1903). 



(4) Ho., 67 (1910) ; 79 (1915). 



(5) Chikyu, 2 (1924), 190; Jap. J. Astr. Geopliys., Abstr., 3 (1925) (2). 



(6) Pub., 22B (1906); T.S.B.K., 2(1904), 164; 2(1905), 433; Phys. Eev., 22 

 (1906),'300. 



(7) Sci. Rep. Toll., [i] 5 (1910), 249; T.S.B.K., 8 (1915), 118. 



