294 



Il \ \'i \uk \ 



riic iico'îilivc liiil — its il iiiiiilil lie callcfl — so cviilciit in J'i"'. 1(1, lias 

 disappeareil in Fig. 11 ; wiiile at tlio saino time, the negative mag- 

 netization lias nuniciMcallv inrrc^ased. I'lit uow passing to the higher 

 loail (see Fig. 12). we see tliat tin' \ai'ioiis changes discussed aliove 

 liaA'c llieir iinal end in a simple single-looped cur\e. with a large 

 ])ortioii in the I'egiou ol' negative magnetization, and with no true 

 minimum points for ^. The twist for which, in the iirst three eases, 

 the value of —^ ehnns'es sii>n. works towards the lel'l as ihe load 

 is increased. Thus 



fnr )r=J.OU , d'r^yldr 

 ,. „ = 527 . 

 „ == ''•■'•"' . 



For IT— 191(1, we may regard this critieal twist as heing loo greal to 

 he included in the range of greatest twist applied. 



It was rc'inarked while discussing the experiment made in the 

 earth's vertical field, that the ratio of the two opposite magnetizations 

 ijraduallv tends to unitv as the load is increased : hut this does not 

 seem to he generally the ease. There is a certain limit beyond which 

 there is an opposite tendencv. I'he fullowing calculations shows that 

 this must lie tlie case. Let + ^s and — !^ Ije the greatest magnetiza- 

 tion during positive and negatix e twists respectively, then in the field 

 — 4.!t I units, and 



W= Go:,; +^==188.0, _;^^ |9.!i. +^^/ -^^ = :',.7H 

 W= OKI; +:^=i;^2.], -^=i:,l.:;. +^/_3 = l.o0 



IF - 12 70 : -t- :.'s = 1 10.:^-, -3^11:'..!. + "s ' - Tv = 1 .0 •"■ 

 jr=1010; + ;;^.:. 8(i.:!, - :\= 77.1. +,\_^. 1.1! 



The following experiments in tield ^- (!.71. show Imw this ratio 

 depends on the strength of the tield. 'fhe changes which the mag- 

 netization curve nnderffoes wliile ii is changinf;' its sii^ri are (|iiite. 



