ee ae a 
+, 
106 Scientific Inielligence. 
read off, and the magnetic force J? of the spiral or of a soft iron bar in 
its axis, determined | by the formula 
ie 
1 ( 1 i 
ae irae weet =J PEL So, Sa Se EG 
i ee (9—a)}4 ss. fora)? 
where J, which in comparative experiments may be regarded as=1 
represents the quantity of magnetism in the steel bar. ‘The author first 
determined the force of the current alone, then introduced a bar of 
the magnetic intensity of the spiral alone and that of the spiral and iron 
core together, gave the magnetic intensity of the core. A number of 
bole iron cylinders, fitting closely into each other, were prepared, 
y means of these and the method of measurement already de- 
saribel, the author arrived at the following conclusions : 
(1.) Electro- magnetism penetrates into “the interior of soft i 
@. ) The more powerful the inducing current the deeper ig pene- 
on. 
(3) Every layer of the soft iron has a point of saturation. 
(4.) The magnetism of hollow and massive cylinders of the same 
kind of iron is of equal intensity, provided that there be a sufficient 
mass of iron present for its evolution. 
And furthermore tha 
“The density of the electro-magnetism upon the surface of soft 
iron is the same for all currents whatever may be their force, and may 
be expressed by the number 7:200.” 
[The researches above mentioned would appear to lead to the conclu- 
sion that every bar of iron magnetized by induction must have a point 
of aegis S at which the magnetism of every layer in the substance of 
e bar would equal that upon the surface, yet it is probable that this 
point of saribalion could never be attained by any force of current 
which we are able to command, at least in the case of bars of any con- 
siderable diameter. ] = 
2. On the law jm the intensity of Magnetism induced in soft iron by 
galvanic currenis.—Burr and ZAMMINER have undertaken an experi- 
mental investigation. not the law of Lenz and Jacobi, that the intensity of 
- 
mine dime’ ‘may be in 
Bent 
is placed horizontally in par position that 
