456 H. A. Rowlund—Studies on Magnetic Distribution. 
TaBLE IV. Bar ‘19 inch diameter. 0 at center of bar. 
Q’e. Q’e- Q. ; R’ 
Ti Ob- Cor- or- jr==. >a =>: 
served. | rected. | rected. R we R 
i 151-7 
2 24:0 24:0 127°7 
3 17°0 17:0 110°7 041 24°4 
4 Iu ist 97:0 0256 39°1 
5 11°6 11°65 85°4 0192 52°] 
6 10°2 10°15 76°2 0168 59°5 
7 9-0 9: 66°2 "0150 667 
8 8-0 8°0 58-2 0153 70°4 
9 71 716 611 “0150 66°7 
10 6-4 6°35 44°7 0142 62°9 
a} 5:7 5°65 39°1 -0160 62°5 
12 4:9 50 34-1 "0167 59°9 
13 4-4 4°4 29°7 “0180 55°6 
14 3°6 3°9 25°8 0184 54°3 
15 3:3 3°4 22-4 ‘01 54:3 
284 22°4 22°4 
tron and not of the magnetizing force. Hence it is for this reason 
that I have preferred in my papers on “ Magnetic Permeability 
to consider it in this way in the formule and also in the plots, 
while Dr. Stoletow in his paper (Phil. Mag., Jan., 1373) plots the 
magnetizing-function as a function of the magnetizing-force. 
When we plot the results in this table with reference to 
Q’ and R’ay, the effect of the variation of R’ is apparent; an 
we see, on comparing the curve with those given m my paper 
above referred to, that R’ increases as L increases, at least 
between L = 2 and L = 8, which is as we should suppose, from 
the arrangement of the apparatus. For this table I happen to 
have data for determining Qin absolute measure, and these show 
that the maximum value of uw should be about where the table 
shows it to be. 
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: and 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 permeabillty- 
* Phil. Mag., August, 1873. 
