284 K. HONDA : ON THE MUTUAL INFLUENCE 



magnetization. Tlie experiment was repeated by Werner Siemens.^^ 

 He wound two coils on an iron tobe, one about the wall of the 

 tube and the other perpendicular to it ; the result of thus 

 magnetizing the tube both longitudinally and transversely at 

 the same time, as examined by means of a magnetometer, led 

 to a considerable diminution of longitudinal magnetization. This 

 result was afterwards confirmed by the experiments of W. H. 

 Schultze,^) C. G. Knott,^) and F. H. Pitcher.^^ 



The effect of longitudinal field on circular magnetization was 

 also examined by Villari^^ with an iron tube. By passing a 

 magnetizing current, the intensity of circular magnetization in- 

 creased, and increased again when the current was removed. 



The present investigation is, to a great part, the critical 

 study of the results already obtained by these physicists. 



I. Arrangement. 



In the present experiment, the intensity of longitudinal 

 magnetization and its change were measured by means of a 

 magnetometer, while the circular magnetization was examined by 

 the ballistic method. 



The magnetometer consisted of a small bell magnet suspend- 

 ed in a thick copper case by a quartz fibre and provided with 

 a plane mirror. It was placed due magnetic west of a magnetizing 

 coil, and its deflection was read by means of a telescope and 

 scale which was 1.90 m. apart from the magnetometer. 



The magnetizing coil was 29 cm. long and wound in two 



1) Berl. Monatsber. 23, Juni 1881 ; Wied. Ann 14, 685, 1881. 



2) Wied. Ann. 24, 643, 1895. 



3) Phil. Mag. 30, 244, 1890; Proc. Roy. Soc. Edinb. 18, 124, 1891. 



4) Pbil. :\rag. 47, 421, 1899. 



5) :\rem. ai Bologna [5] 2, 443, 1892 ; Beibl. 17, 670. 



