Mr. K. H. M. Bosanquet on Electromagnets. 343 



The following Table contains the conductivities of the bars 

 with pole-pieces, as obtained from the experimental magnetic 

 resistances, and their comparison with some of the different 

 methods which may be or have been adopted for representing 

 the law of magnetism. These methods are enumerated in the 

 following statement, the table only containing such compa- 

 risons as seem necessary. 



Numerical Comparison with Experiments of some of the 

 Calculations representing the Magnetic Conductivity of 

 Bars 1 : 20 with Pole-pieces. 



33. 



Conduc- 

 tivity or 



P 

 from ex- 



II. Fourier Series. 



III. Rule with 

 approximate /*. 



IV. Tangent law. 



1 



Diffs. 



1 



Diffs. 



1 



Diffs. 





periment. 



P 





P 





P 





0,000 



169 



187 



+18 



171 



+ 2 







1,000 



271 



245 



-26 



252 



-19 



614 





2,000 



301 



290 



-11 



289 



-12 



610 





3,000 



319 



316 



- 3 



310 



- 9 



603 





4,000 



332 



326 



- 6 



323 



- 9 



592 





5,000 



337 



332 



- 5 



330 



- 7 



578 





6,000 



340 



337 



- 3 



334 



- 6 



561 





7,000 



340 



340 







338 



- 2 



541 





8,000 



340 



340 







339 



- 1 



518 





9,000 



339 



339 







338 



- 1 



490 





10,000 



336 



337 



+ 1 



334 



- 2 



459 





11,000 



332 



331 



- 1 



330 



- 2 



424 





12,000 



324 



327 



+ 3 



323 



- 1 



385 



4-61 



13,000 



310 



312 



+ 2 



310 







341 



4-31 



14,000 



286 



283 



- 3 



289 



+ 3 



292 



+ 6 



15,000 



238 



233 



- 5 



252 



4-14 



238 







16,000 



171 



175 



+ 4 



171 







171 







17,000 



136 



130 



- 6 







110 



-26 



18,000 



91 



104 



+ 13 







36 



-55 



Statement of Methods for representing Conductivities by 

 Calculation. 



I. By value of -, where p is derived from my theory : see 



Phil. Mag. vol. xxii. p. 308 (September 1886). (The formulse 

 at the head of the tables at pp. 307 & 308 have been unfor- 

 tunately wrongly copied. I give the correct headings com- 

 plete in the Errata at the end of this paper.) 



This representation is quite close, but the computations are 

 rather too laborious for ordinary use. It is not necessary to 

 exhibit the comparison. 



II. Empirical representation of conductivities by Fourier's 



