222 KNOTT AND TÂNAKADATE 



Section V. 

 Comparison of Present with Former Results. 



This Section will necessarily be a short one, inasmuch as magnetic 

 measurements made in Japan have been somewhat hmited in number. 

 Excepting the observations made by Messrs. Sekino and Kôdari, and 

 tlie few made by Mr. Schutt already referred to, no complete satisfac- 

 tory (observations have been made at any stations out of Tokyo. 



During the vari(Mis expeditions sent out from year to year by 

 the Tokyo University for the measurement of the force of gravity by 

 pendulum swinging, attempts were made at the same time to obtain 

 measurements of certain of the magnetic constants. The first ex- 

 pedition of this kind was to the top of Fuji-yama under the direction 

 of Professor Mendenhall. This was in the year 1880. In 1881, 

 Messrs. Tanakadate, Fujisawa, and Tanaka, then students of physics, 

 who had rendered efficient service in the first expedition, proceeded to 

 Sapporo accompanied Ijy Professor Chaplin, and there made like 

 (observations on gravity. In 1882, the expedition, consisting of Mr. 

 Tanakadate, and two students of Physics, Messrs. Sakai and Yama- 

 guchi, proceeded to Kagosliima and Naha, in the extreme South-west 

 of Ja|)an. And finally in 188-i, Mr. Tanakadate accompanied by 

 Messrs. Sawai, Ilayasaki, and Saneyoshi, three students of Physics, 

 proceeded to the Bonin Islands and there swung their pendulums. 

 In all these expeditions magnetic measurements of a kind were made. 

 In the third expedition only was any attempt made to measure the 

 dip. This was done by balanchig the inductive action of the earth's 

 field upon an iron wire by means of a current circulating in a helix 

 surrounding the wire. The wdre and hehx were placed alternately 

 vertical and horizontal ; and the ratio of the current strengths 

 required to effect the balance in the two cases gave the tangent of the 



