134 Messrs. Bottomley and Tanakadat^ on 



nished readings. The scale used is graduated from at the 

 left hand to 1000 at the other extremity. 



The foregoing brief description of the apparatus used will 

 be considered sufficient in a note like the present. 



The nickel wire used was 1"58 millim. in diameter. It is 

 of excellent quality, though not guaranteed perfectly pure. 

 The first wire used was 63 centim. long ; a second wire, which 

 was used inside a solenoid, was 5 or 6 centim. longer. After 

 being hung up, the wire was several times heated to redness 

 at every part by passing a Bunsen-flame up and down it. 

 The scale-pan and a small weight were kept hanging on the 

 Mare during this heatino- which was with care carried out to 

 the very extremities of the wire. 



The wire was then very carefully lifted down, shocks being 

 avoided ; the zero of the magnetometer was ascertained; 

 the wire was replaced, and the scale-pan first and then the 

 stretching-load were cautiously applied. The heating process 

 was repeated when, after any usage to which the wire had 

 been subjected, it was judged that irregularity of magneti- 

 zation might have been introduced. 



After a few preliminary trials had been made with small 

 loads, all of which seemed to verify conclusions which would 

 be represented by Mr. Nagaoka's curves (figs. 1 and 2), 

 the wire was reheated and a load of 12 '49 kilogs., or 640 

 kilogs. weight per square centimetre, was applied. This it was 

 considered ought to give results such as would be represented 

 by fig. 3 of the original paper. The following table shows the 

 results of this experiment, and the readings under twist fully 

 confirm Mr. Nagaoka's corresponding experiment. 



Table I. 



Magnetic field 0-46 C.G.S.* 



Magnetometer zero 500 



Wire in position with very small stretching- ) poc 



weight "" J 



Load gradually applied. 



Load, in Magnetometer- 



kilogs. reading. 



3-63 620 



5-41 603 



6-84 588 



9-77 570 



12-49 560 



* Calculated from information kindly supplied to us by Prof. Riicker, 

 F.R.S, 



