Viscosity and Rigidity of Iron and of Steel. 179 



shows that when the current is passed through the helix differ- 

 entially, (p increases at the same rate as before, notwithstanding 

 the fact that the field is now zero. Hence the amount of vis- 

 cous detorsion observed is a temperature discrepancy and no 

 viscous effect due to magnetization is discernible. 



Table 2. 



Viscosity of magnetized iron. Rods Nos. 7, 8, annealed soft. Z=i30 cm ; 2p=s 

 0-110 cm ; f=20 o : r=— 3-6°. 



h 



0xlO 6 



t 



Circuit. 



h 



0xlO 6 



* 



Circuit. 



000 

 0-57 

 0-58 

 0-92 

 1-23 







— 3 



+ 65 

 30 



8 

 -58 

 -53 

 + 18 

 + 10 







— 3 



— 71 

 -60 



— 52 



33 

 34 

 33 



28 



29 

 33 

 34 

 34 

 29 

 26 



t Open. 

 [■ Closed. 



[• Open. 



1 



\ Closed. 



i 



J 



>- Open. 



3-48 

 3-68 

 4-05 

 4-05 



4-47 



+ 15 

 + 4 

 — 5 

 -72 

 -62 



26 

 30 

 34 

 34 

 29 



[ Closed. 

 [• Open. 



1-23 



1-80 

 1-85 

 2-00 

 2-17 

 2-48 

 2-50 

 2-97 

 3-47 



4-52 

 4-75 

 4-92 

 5-07 

 5-38 

 5'56 

 22-30 



— 55 

 -65 



— 63 

 -70 

 -73 

 -73 

 -50 



32 

 33 

 34 





Closed dif- 

 ferentially; 

 ' magnetic ; 

 field zero. 



• Open. 



In table 3, I give similar results with a thinner wire. 



Table 3. 

 Viscosity of magnetized iron. Z=30 cm ; 2p=0-083 cm ; f=20° ; r=— 3°. 



h 



<j>xl0 6 



t 



Circuit. 



h 



0xlO 6 



t 



Circuit. 



o-oo 







"T" 



J- Open. 



5-13 



310 





) 



0-38 



80 



__ 



5-57 



328 



25 



> Open. 



.0-42 



189 



21 



1 



23-00 



545 



18 



) 



0'50 



195 



21 



1 



23-10 



653 





1 



y Closed. 



0-75 



220 



26 



Y Closed. 



23-33 



645 





1-05 



245 



29 



1 



23-67 



643 



28 



1-38 



265 



30 



J 



24-00 



645 



30 



J 



1-42 



161 



30 



1 



24-05 



538 



30 



) 



1-68 



183 



28 



VOpen. 



24-42 



550 



26 



v Open. 



1-95 



203 



25 



24-95 



560 



23 



) 



2-17 



218 



23 



J 



24-97 



670 





) 



2-18 



328 



24 



i 



25-33 



660 



28 



l Closed. 



2-48 



334 



27 



I Closed. 



26-17 



668 



32 



( 



2'88 



348 



30 



26-20 



561 





1 Open. 



3-23 



360 



32 



J 



27-12 



580 



23 



3-25 



255 





) 



27-27 



690 





j- Closed. 



3-50 



270 





>• Open. 



28-28 



685 



31 



4-17 



298 





i 



28-35 



580 





(• Open. 



4-20 



407 





) 



48-00 



740 





4-67 



410 



28 



y Closed. 











5-08 



420 



30 



) 











