1889 - 90 .] Prof. Knott on Interactions of Magnetisations. 403 
(3) Observing the initial effect when the linear current was 
broken, and taking again the permanent magnetic cycle, 
as in (1); 
(4) Observing the initial effect of the linear current put on in 
the other direction, and taking the permanent magnetic 
cycle with this current steady; 
(5) Operating as in (3). 
It was soon found that in good experiments the permanent 
magnetic cycles in (1), (3), and (5) were practically identical ; so 
that in later experiments (3) was omitted. It was also established 
by direct experiment that the permanent magnetic cycle in (2) was 
quite independent of the magnetic condition of the wire when the 
linear current was put on. 
Some of the features of the case are shown in the curves given. 
This is chosen as an average type, the departures from which, when 
the relative magnitudes of linear current and field are altered, will 
be briefly indicated below. In these curves magnetic force (t£j) is 
measured horizontally ; magnetic intensity (!£) measured vertically. 
The magnetic force is given in electromagnetic c.g.s. units, and the 
magnetic intensity (very roughly) in the same. 
