Permeability of Iron and Steel. 83 
probable that Weber’s theory may be so modified as to give 
an equation of the type he employs. I am not aware that 
. this has been attempted, and it seems improbable on account 
of the nature of the equation. Further it is clear that the 
functions involved are continuous through the whole range 
of the magnetization. And the essence of Weber’s theory 
and of all modifications of it is to divide the course of events 
into separate portions, in which different causes are supposed to 
operate, and different expressions are obtained for the results. 
The statement that the results are continuous applies to 
the residual subpermanent magnetism as well as to that ob- 
tained by reversal; for although I have not made any deter- 
minations of residual magnetism, the data in Rowland’s 
table I. are sufficient to give a series of values of residual 
magnetism which determine the point. Using the same 
angle proportional to the total induction for 6, we can find a 
new quantity pw’, which we may call susceptibility to residual 
magnetism. 
The following table gives the results of this process as 
applied to Rowland’s table I.:— 
% or Q, total induction by reversal. 
%/ or P, subpermanent or residual induction (Q—T). 
#, Rowland’s value of the permeability. 
if 1 3 
; LB 
| eae — 
Then, if w/= potential’ 
potential in the same way that w= 
p= ps = 
from which the following values are calculated :— 
Initial values ‘ nea from first and third lines, by 
differences. ae 
pe’ or Susceptibility to Subpermanent Magnetism, from 
Rowland’s table I. 
! 
3. 35’. | | B. 33’. 
Q Pepe: pe. 
| 71:5 18-7; 390°7 102-7 || 8943 6369 2208 1572 
600°5 2111; 868°7 305°4 | 10080 6838 1899 1288 
966°7 438°7| 1129 512:4 |! 12270 7502 1448 885 
| 2460 1572 | 1986 1237 12970 7666 1269 750 
| 2923 1942 2078 1380 13630 | 7520 1137 aR 
| 8082 2064 2124 1422 14540 | 7989 824-1} 452°8 | 
4959 | 3628 | 2433 | 1780 | 15770 | 8116 | 4618! 937-6 
5482 | 3811 | 2470 | 1717 || 16270 | 7852 | 353-8] 170-7 | 
2472 | 1715 || 16600 .| 7888 | 258 | 1996 
6651 | 4746 | 2448 | 1747 || 17500 
7473 | 5434 | 29367 | 1721 | | 
