20 H. A. Rowland — Studies on Magnetic Distribution. 



In these tables the decrease of steepness is not very apparent, 

 because the magnetization is always too great, and indeed on 

 this account it is difficult to show it; but in Tables V, YI and 

 VII. this action is shown to some extent by the values of r in 

 the formulae. The change of distribution with the helix 

 arranged in this way at the center of the bar is greater than in 

 almost every other case, because the magnetism of the bar Q" 

 can change greatly throughout the whole length of the helix, 

 and thus the value of r be changed, and so the distribution 

 become different 



The next case of distribution which I shall consider is that 

 of a very long rod having a helix wound closely around it for 

 some distance at one end. 



Table X. is from a bar 9 feet long with a helix wound for 

 one foot along one end. The bar was '25 inch in diameter. All 

 except the first column is the sum of two results with the cur- 

 rent in opposite directions, and after letting the bar stand for 

 some time, as indeed was done in nearly every case. The first 

 column contains twice the quantities observed, so as to com- 

 pare with the others. The zero-point was at the end of the 

 bar covered by the helix. 



X and L. 



A. 



B. 



C. 



D. 







•360. 





1-09. 



? 



XV. 



:f6--^ 



X^l 



+ 60-1 





X 2-0 



X 4-6 



:i 



+ 22-8 





- 1-8 



- 1-6 



- 2-1 



- -3 



10 



- ^."9 



- 6-3 



- 8-6 



- 15-6 









-16-4 



- 27-1 





























-12-5 



- 210 





















- 31-2 



20 





- 5-3 



-15-2 















48 





"" ' 



- 12 





The value of Q"e between and 1 includes the lines of force 

 passing out at the end of the bar, and is therefore too large. 



