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solenoid, we heard during the exponential increase of the current after 
it was closed a very great number (not yet estimable numerically) 
of claps within a short interval. At the end, when the current 
had nearly reached its maximum value, some isolated discontinuous 
magnetisation-changes were distinctly audible. 
After that one single isolated discontinuity was thus observed, the 
variation of the intensity of the field by means of a current was 
no longer used and we returned to the movable permanent magnet. 
This time however the magnet was fixed to a support that was 
adjustable by means of a micrometer-screw. In this way the distance 
between the magnet and the nickel-steel rod which was to be 
magnetised, could be changed very continuously by turning a small 
handle. The magnet was fixed with the poles vertically above each 
other at the same height as the solenoid surrounding the nickel-steel 
rod, and at a distance from it of about 5 cm. By means of a second 
magnet, a remanent magnetism.was now given to the rod in such 
a sense that it was decreased by the approach of the micrometrically 
adjusted first magnet. By gradually changing the position of this first 
magnet the intensity of the field could be changed very slowly ina 
continuous way. In this way the discontinuous reversals of the 
magnetism of, in our opinion, long crystal groups may be investigated 
in greater detail and the discontinuities can be heard isolated. 
With the arrangement described above the following phenomenon 
was found. When the magnet was quickly brought 1 m.m. nearer 
to the nickel-steel rod, of course the described claps were heard. 
But also afterwards, when by keeping the magnet fixed in the new 
position, the field was thus kept constant, we could distinctly hear 
in the telephones still several discontinuous magnetisation changes. 
The last discontinuities were heard sometimes 7 seconds after the 
field had remained constant. 
The great intensity, with which in nickel-steel the general pheno- 
menon was detectable, enabled us to investigate the discontinuities 
in the magnetisation also galvanometrically. To this end the solenoid 
was connected directly (without amplifier) to a SieMeNs and HALSKE 
galvanometer, system resistance 300 Ohm. With the external connection 
of the instrument to the solenoid, it was not damped to such an 
extend as is the case with the Grassot-fluxmeter, where the deflection 
obtained by an induction-pulse, remains practically constant for minutes. 
A slowly creeping back after an induction pulse could not be avoided. 
But still, notwithstanding this insufficient damping, the ideal property of 
the flaxmeter was approximately obtained, in which the galvanometer coil 
always tries to take up such a position that the total flux through the 
