MAGNETISM AND TWIST IN IRON AND NICKEL. 



379 



bination is always smaller for the higher tension. An increase of tension from 80 to 300 

 kilogrammes weight per square centimetre is sufficient in some cases to diminish the twist 

 due to a given combination of magnetisms to one-fourth of its original amount. In the 

 following tables only the maximum twists are given, as it hardly seemed necessary to 

 reproduce all the individual observations. We can safely employ these maximum twists, 

 because of the first conclusion given above, namely, the absence of any recognisable 

 relation between the tension and the longitudinal field corresponding to the maximum 

 twist. 



In these tables the symbols have the following meanings : — 



r = radius of wire in centimetres. 



C = current along the wire in amperes. 



H = mean value of longitudinal magnetic field corresponding to the maximum 

 twist. 



H' = C/5r = circular magnetic field at the circumference of the wire. 



T = tension in kilogrammes weight per square centimetre. 



6 = angular displacement, measured in radians, of any cross-section of the wire 

 relatively to the cross-section 1 cm. distant from it. 









Table I 



— Iron 



Wires. 









No. 1. 



r=02. 



No. 2 



{continued,). 



. No. 2 



{continued). 





T 



104-0 





T 



104-0 





T 



10- 4 e 



C = 1-14 



196 



4-60 





543 



2-81 





1630 



1-97 



H=10-5 



594 



425 





698 



25 





1785 



1-75 



H'=11'4 



992 



335 





853 



225 





1940 



1-69 





1388 



255 





1087 



197 





2093 



1-56 





1784 



235 





1164 



1-88 





2256 



1-56 





2181 



1-60 





1312 



190 





2463 



1-22 





2577 



1-55 





1630 



1-47 





2618 



116 





2975 



115 





1785 

 2093 



134 

 119 





2773 



1087 



77 



103 



2-69 

 3-84 



C = 173 



196 



500 





2256 



110 





H = 14-0 

 H' = l7-3 



594 

 992 



435 

 400 





2463 

 2618 



•90 



■84 















1388 



325 





2773 



•81 



No. 3. 



r=-04I5. 





1784 



300 





1087 



206 















2181 



235 





77 



350 





T 



104-0 





2577 



1-90 

















C = 152 

 H=ll-8 



77 

 232 



3-94 

 3-78 



C =1-08 

 H=7l 



48 

 243 



2-96 

 243 







No. 2. 



r = -032. 



H'= 95 



388 



3-69 



H' = 52 



439 



2-02 









543 



334 





633 



1-76 











T 



lO 4 -0 





698 



300 





864 



1-28 











853 



1087 



2-88 

 269 





1058 



1-18 



C = -95 



77 



375 







1251 



104 



H =10-4 



232 



3-44 





1164 



2-44 





1413 



•92 



H'= 5-9 



388 



314 





1312 



219 





1661 



•67 



