MAGNETIC PERMEABILITY OF NICKEL AND COBALT 



63 



TABLE III. 



CAST NICKEL, MAGNETIC, AT 220 C. 

 Experiments made December 6, 1873. 



In Table I are given the results for nickel at about 15 C., together 

 with the values of // and < calculated from the formulae given below the 

 Table. We see that the coincidence is almost perfect in both cases, 

 which thus shows that the formula which we have hitherto used for X 

 and ;j. can also be applied to , at least within the limit of experiments 

 hitherto made, although it must at last depart from one or the other 

 of the curves. The greatest relative error is seen to be in the first 

 line, where ) is small: this does not indicate any departure from the 

 curve, but is only due to the too small deflections Of the galvanometer; 

 and the error indicates that of only a small fraction of a division at the 

 galvanometer. 



In the calculation of /J- and K a method was used which may be of 

 use to others in like circumstances, who have to calculate a large num- 

 ber of values of one variable from a function which cannot be solved 

 with reference to that variable, but can be solved with reference to the 

 other. Thus we have 



which can be solved with reference to S3 but not to //; for we have 



(1) 



(2) 



