4 ART. 1. — K. HOXDA AND Ï. TEEADA. 



(b) Ditto by Barus's method. 



(c) Ditto by the ordinary method. 



The specimens tested in the present experiment were Swedish 

 iron, tungsten steel, nickel, and nickel steels of different percen- 

 tages. They were generally tested in the form of wires. For 

 the change of rigidity, the rod was also used in the case of 

 nickel and iron. 



§ 2. EXPERIIVIENTS ON THE CHANGE OF ELASTI- 

 CITY BY IVIAGNETIZATION. 



(a) IVIeasureinent of the change of elasticity by 

 the elongation method. 



Since the elongation due to the change of elasticity is a 

 small fraction of the total elongation, it Avas desirable to devise 

 some differential method. For this purpose, the elastic elonga- 

 tion at no field was compensated by that of a non-magnetic wire, 

 and the differential elongation due to magnetic field was observed. 

 As shown in the annexed figure, the magnetic wire to be tested 

 and the compensating copper wire were hung side by side in the 

 vertical magnetizing coil cc. To both ends of the wires were 

 brazed brass rods bb, whose elongation could be neglected. The 

 upper rods were hung separately on two horizontal brass beams 

 aa resting on pairs of knife-edges, the distance between which 

 could be adjusted at will. To tlie lower rod attached to the 

 copper wire, a light carriage vi for a mirror system was clamped. 

 Two Ihie spiral springs ss of german silver attached to the sides 

 of the carriage, supported horizontally the axis of the light mir- 

 ror with a suitable counterpoising. The lower rod for the mag- 

 netic wire carried a flexible band / made of a bundle of very 



