642 
whole circuit (galvanometer-coil -+ solenoid) remains constant. 
When now the magnetisation of the nickel-steel were perfectly con- 
tinuous, the continuous approach of the magnet should give 
rise to a gradual increase of the galvanometer deflection, while this 
should remain approximately constant, when the field did not change 
any longer. The discontinuities that occur in reality in the induction 
during a continuous change of the field become manifest by the jumps 
of the galvanometer deflections. With a scale-distance of 4 m. we 
observed jumps from 5 to 7 m.m. (scale divisions) during perfectly 
continuous changes of the field. . 
Between these jumps small periods were observed during which the 
induction, as far as could be observed at least, increased continuously 
together with the magnetic force. 
When after the field had inereased for some time, which was 
accompanied by the discontinuities, the field was weakened again 
by taking the magnet away a certain distance (say a few m.m.) 
and afterwards again increased beyond the point first reached; 
then however no discontinuous changes in the magnetisation occur 
neither during the weakening nor during the increase up to the 
point where the field had reached the previous value. 
As soon however as this point is passed, the discontinuities are 
again observed with the same intensity as before. Compared with 
the intensity of the field the continuous increase and the preceding 
decrease of the induction are much slower than in the discontinuous 
region. The described phenomenon is represented schematically by 
fig. 1, where the curve was described in the direction of the arrows. 
Fig. 1. Fig. 2. 
