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Proceedings of the Royal Society of Edinburgh. [Sess. 
impediments ? It is not easy to see how it can, unless the rearrangement 
of the molecules opens up the channels along which the electrons may pass. 
This seems to require that the forms of the magnetic whirls are such 
that they present less obstruction when they are facing across the strip 
than when they are facing along it. This supposition would explain the 
two main effects. But how far will it go in explanation of the complex 
results which are the subject of this paper ? 
On any of the more usual conceptions of the molecular movements 
which accompany magnetization, a longitudinal field will always tend to 
turn the magnetic whirls so as to face more in the direction of the length 
of the strip. Similarly, if the magnetic molecules are turned so as to face 
along the strip under the influence of the longitudinal field, the effect of the 
superposed transverse field will be to turn the magnetic whirls round so 
as to face obliquely across the strip. But, if the molecules present less 
obstruction when they face across the strip than when they face along it, 
it is not easy to see how intermediate orientations, such as would be 
produced under the combined influence of the two fields, should be ac- 
companied by a still further increase of conductance. In short, no simple 
theory of orientation of magnetic molecules can at all fit in with the facts. 
We must look for an explanation to some more complex process in which 
the grouping of the magnetic molecules, and even the internal structure of 
each magnetic molecule, are of fundamental importance. 
Before further discussion, however, it will be useful to make similar 
experiments with iron or steel ribbon. In their magnetic behaviour iron 
and nickel present both similarities and contrasts ; and it cannot fail to be 
of interest to compare their properties in regard to the present line of 
inquiry also. This comparison I hope to make in a few months. 
