260 
Proceedings of the Royal Society of Edinburgh. [Sess. 
The steel core formed a circle of 6 cm. diameter, and the iron core one of 
7*3 cm. diameter. The larger size of the iron core accounts for the greater 
number of windings in each layer. 
Applying the usual approximate formula, we find that a current of one 
ampere passing through the magnetizing coils will produce fields of 53*7 
and 59*6 in the steel-core and the iron-core anchor-ring respectively. 
The transverse field was applied by means of a specially designed 
electromagnet with cylindrical pole pieces, the air gap between which 
could be altered with ease. The anchor-ring coil under investigation was 
placed symmetrically in the air gap, so that the axis of the anchor-ring 
passed through the centres of the pole pieces. The magnetic fields 
established in the air gap for various lengths of air gap and strengths of 
current passed through the coils of the electromagnetic were measured by 
means of a Grassot Fluxmeter. The lines of force established in the air 
gap ran across the coiled strip of iron or steel, that is, transverse to the 
direction in which the resistance was being measured. 
The method of experimenting was identical with that described in 
detail in the former paper (1). 
The iron or steel strip formed the greater part of one arm of a Wheat- 
stone Bridge, an approximate balancing being secured by adjustment of 
the point of contact on a stretched wire. The combined system of con- 
ductors forming the Wheatstone Bridge was made part of a circuit 
through which a small steady current was passed from a secondary cell. 
When this current was flowing steadily through the circuit, one of the 
known resistances in the Bridge was altered slightly in a definite manner 
by introducing a large resistance shunt in parallel with this resistance. 
The deflection obtained on the galvanometer, being due to a measurable 
disturbance in the balance, was essentially a standardizing of the deflec- 
tion. This calibrating shunt being thrown out of connection, the iron or 
steel strip which formed the opposing branch in the Bridge was then 
magnetized. The disturbance due to this cause at once declared itself by 
a corresponding deflection on the galvanometer scale. This deflection, 
taken in conjunction with the deflection formerly produced in the standard- 
izing experiment, gave the means of calculating the change of resistance 
accompanying a given magnetization. 
The galvanometer used in these experiments was a D’Arsonval galvano- 
meter of the Ayrton-Mather design, and was found eminently satisfactory 
on account of its steadiness and sensitiveness. 
As in the previous experiments with nickel, the deflections were obtained 
by reversing the steady current through the Wheatstone Bridge, the 
