360 Mr. H. A. Rowland on Magnetic Distribution. 



Table XIV. 



, 



Qc 



Observed. 



4tt\. 

 Observed. 



4,r\. 

 Computed. 



Error. 







1-28 

 2-56 

 3-84 

 512 

 6-40 



42-6 



214 



10-9 



5-4 



17 



31-9 



167 



8-5 



4-2 



1-33 



3074 



1672 



8-86 



4-28 



1-27 



-1-2 

 



4- 4 

 + 1 

 - 1 



4 7 rX = -105(10' 203 ( 6 - a; )-10 ,20to ). 



The coincidence of these observations with the formula is very 

 remarkable ; but still we see a little tendency in the end obser- 

 vation to rise above the value given by the formula. 



In equation (7), and also from Green's formula, we have seen 



that for a given quality and temper of steel p= — is a constant. 



From Coulomb's experiments on a steel bar "176 inch in dia- 

 meter (whose quality and temper is unknown, though it was 

 probably hardened) Green has calculated the value of this con- 

 stant, and obtained "05482, which was found from the French 

 inch as the unit of length, but which is constant for all systems. 

 From Tables XIII. and XIV. we find the value of r to be -4674, 



rd 

 whence ^- =-04440 for steel not hardened. As the steel be- 



comes harder this quantity increases, and can probably reach 

 about twice this for very hard steel. 



To show the effect of hardening, I broke the bar used in 

 Table XIV. at the centre, thus producing two bars 6*4 inches 

 long. One of these halves was hardened till it could scarcely be 

 scratched by a file ; but the other half was left unaltered. The 

 following Table gives the distribution, using the same unit as 

 that of Tables XIII. and XIV. The bars were so short that 

 the results can hardly be relied on ; but they will at least suffice 

 to show the change. 



Table XV. 



X. 



Soft steel, A. 



Hard steel, B. 



Qe. 



4ttX. 



Qe. 



4tt\. 







•64 

 1-28 



1-92 

 3 20 



20-4 

 9-8 

 60 

 3-8 



291 



15 3 



9-4 



30 



477 



139 



70 



2-6 



681 



217 

 110 

 ,0 | 



