352 H. XAGAOKA. 



reversed in direction. This was done by means of a rocker com- 

 mutator placed in circuit with the magnetizing solenoid. With the 

 wire kept steadily twisted either on the right or left hand side of the 

 initial position of no torsion after repeated to and fro twistings, a 

 magnetizing force was applied. On reversing the direction of the 

 magnetizing force a momentary current passed through the galvano- 

 meter coil. In general the deflection of the galvanometer magnet set- 

 tled to a constant value after numerous reversals, upon which the swing 

 of the galvanometer magnet corresponding to a reversal was noted. 

 The wire was then twisted in the opposite direction, and after numer- 

 ous reversals of the magnetizing force, the deflection of the galvano- 

 meter magnet was again noted. The mean of these Uvo readings was 

 taken as a measure of the transient current. It should he noted that 

 the direction of the transient current is reversed when either the tw r ist 

 is reversed or the direction of current reversal is changed. 



The first set of experiments made in this way was by varying the 

 magnetizing force, the amount of twist remaining constant. The 

 iron wire used was 1.24 mm. thick and 27 cm. long. Instead of giving 

 the observed numbers, I refer to curves plotted in Fig. III. (Plate 

 XXIX.) These show at a glance the relation between the current 

 and the magnetizing force for different amounts of twist. These 

 curves were obtained for the following different angles of torsion. 

 Curve I for the twist of ± 5°, 



5? ^ ,, ,, ,, >>i^o, 



» HI ,, „ ,, „ ± 30°, 



5j IV ,, ., „ „ ± 60°, 

 V +120° 



The general feature of all these curves are similar to those 

 obtained by twisting the wire through a given angle in different mag- 

 netizing fields. The transient current increases on the application of 



