643 
The detailed structure of the discontinuities in the induction as they 
have been observed with the galvanometer, is roughly indicated 
in fig. 2. It is seen that as a rule the value of B before making a 
jump, remains constant a little while. The smallness of the jumps 
and the insufficient damping of the galvanometer, however, rendered 
the observations very difficult. 
By connecting the solenoid round the nickel-steel rod both with 
the galvanometer and with the triode-amplifier, the stronger claps 
could be indentified with the greater jumps in the galvanometer 
deflections. The weaker claps however could not be observed 
galvanometrically. 
Finally the order of magnitude of the discontinuities in the induction 
was determined for nickel-steel. 
To that purpose a second coil (diameter 8,65 mm., one layer of 
50 windings of length 45 mm.) was placed inside the first solenoid. 
A pulse of the current of 40 milli-ampere was necessary to obtain 
a leap in the galvanometer deflection of the same order of 
magnitude as those observed during the magnetisation of the nickel- 
steel. The intensity of the field in the coil was therefore : 
50 
TRE 1, teonp. = Hs 15 0,04 = 0,56 Gauss. 
We thus find for the change of the flux through a winding of 
the solenoid 
0.865? 
aN 9 (5) 0,56 = 0,33 lines of force. 
When therefore we assume the conception above described of the 
change of sign of magnetisation of long filaments to be correct, we 
should find for the order of magnitude of the cross-section of such 
a fibre of the ferro-magnetic nickel-steel : 
0.33 
18000 
on the assumption of a maximum induction 18000 as for iron. 
Assuming: finally a cylindrical form we find for the diameter: 
0,05 mm., 
a not quite improbable value. These calculations are however to be 
regarded as preliminary; further investigations being indispensable 
to bring more clearness in this complicated phenomenon. 
= 1,83 10-2cem-- 
