274 Mr. H. A. Rowland on Magnetic Distribution, 



This method of finding the variation of //, is analogous to that 

 of finding conductivity for heat by raising the temperature of 

 one end of a bar and noting the distribution of heat over the 

 bar ; indeed the curves of distribution are nearly the same in 

 the two cases. 



If it were thought worth while, it would be very easy to ob- 

 tain a curve of magnetic distribution for a rod and then enclose 

 the whole rod in a helix and determine its curve of permeability. 

 This would give data for determining R/ in absolute measure at 

 every point of the rod. 



To complete the argument that the variation of r 2 is in great 

 measure due to that of //,, I have caused the magnetizing force 

 on a bar to vary. Tables V., VI., and VII. are from a bar 9 

 feet long and *25 inch in diameter. At the centre a single layer 

 of fine wire was wound for a distance of 1 foot ; and the current 

 for magnetizing the bar was sent through this. The zero-point 

 was at the centre of this helix and at the centre of the bar ; so 

 that the observations on the first 6 inches include the part of 

 the bar covered by the helix. 



The values of Q' e are the sum of four observations on each end 

 of the bar and with the current reversed. The three Tables are 

 comparable with each other, the same arbitrary unit being used 

 for all. 



Table V. 

 Magnetizing current *176. 



L. 



Q'e. 



Ob- 

 served. 



Q'e- 



Cor- 

 rected. 



Q'. 



Cor- 

 rected. 





1_R' 



r* R'' 



Q"e. 



Calcu- 

 lated. 







1 



2 



3 



4 



5 



6 



7 



8 



9 



10 

 11 

 12 

 13 



»} 



!? 



18 J 

 End. 



27 

 6-9 

 127 

 18-2 

 24 4 

 32-4 

 31-5 

 28-2 

 24-9 

 21-4 

 18-6 

 16-8 

 14-2 

 120 



177 



11-6 

 22-4 



317 



320 



28-2 



247 



217 



190 



16-4 



14-2 



120 



100 



8-2 



6-6 



51 



22-4 



220-5 



188-5 



160-3 



135-6 



113-9 



94-9 



78-5 



64-3 



523 



42-3 



341 



27-5 



224 



: 0190 

 •0212 

 •0218 

 0236 

 •0252 

 •0278 

 0311 

 0367 

 •0404 

 :0440 

 •0445 

 •0570 



52 : 4 

 472 

 459 

 42-4 

 397 

 360 

 32-2 

 272 

 24-8 

 227 

 225 

 175 



2-40 



7-32 



1254 



18-31 



24-87 

 32-38 



IP 



1 



CO 

 CO 



**- 



© 



o 

 <o 

 ©^ 



1 

 1 



© 



© 



to 



