The sample to be examined is introduced and suspended from a non-magnetic metal rod bent in the form of an L by means of an untwisted thread. The rod passes lengthwise through a lathed wooden plug lying on the bell and fitting the circular hole with a certain play.
By moving the rod, which extends through the top of the plug, up and down, it is possible to regulate the position of the sample with respect to the poles of the electromagnet from the outside.
The faces of the extensions are straight sections of the soft iron toroidal nucleus. They are therefore circular and converge towards the centre of the toroid going from a distance of 1.73 cm to one of 1.46 cm between them.
The magnetic field between the expansions is thus not uniform and is more intense where the expansions are closest.
A small sample, either squared or rounded, introduced between the expansions when the electromagnet is not active, if electricity is applied, will be attracted towards the region in which the expansions are closest and the field is strongest if it is paramagnetic and towards the region in which the expansions are farthest away and the field is weakest if it is diamagnetic.
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