THE 
LONDON, EDINBURGH, ann DUBLIN 
PHILOSOPHICAL MAGAZINE 
AND 
JOURNAL OF SCIENCE. 
[FIFTH SERIES.] 
FEBRUARY 1885. 
XI. Electromagnets—II. On the Magnetic Permeability of 
Lron and Steel, with a new Theory of Magnetism. By R.H. 
M. BosanquEt, St. John’s College, Oxford. 
To the Editors of the Philosophical Magazine and Journal. 
GENTLEMEN, 
ORs attempting to draw rigorous experimental con- 
clusions as to the effect of the magnetic properties of 
Tron and Steel on electromagnets made of these metals, it is 
necessary to obtain some further information as to the mag- 
netic properties in question. 
Hitherto I have accepted the results of Rowland’s experi- 
ments with rings*; but I have now repeated and varied these 
experiments, with special regard to the following points:— 
To find the average properties assigned by this method to 
the Iron and Steel I commonly use; 
To assign to the results formule of a more general and 
more manageable type than that employed by Rowland ; 
And to justify experimentally the assumption that the per- 
meability, as calculated from the experiments, is independent 
of the size and proportions of the rings examined. 
A new theory of these magnetic properties will be enun- 
ciated and applied. 
The iron upon which most of the following experiments 
have been made is what is called ordinary bar-iron. It is 
what I commonly use for electromagnets. It is moderately 
soft and admits of being easily forged. It is stamped with a 
* Phil. Mag. [4] xlvi. p. 140 (1878). 
Phil. Mag. 8. 5. Vol. 19. No. 117. Feb. 1885. G 
