1890 - 91 .] Prof. C. G. Knott on Magnetism and Tivist. 319 
twisting a magnetised wire, more especially a wire magnetised 
circularly by a current passing along it. The peculiar manner in 
which the magnetic change sometimes lags behind the stress, some- 
times shoots ahead of it, is fully investigated. This magnetic 
“ lagging ” or “ priming ” is found to depend upon the strength of 
the current, upon the amount of twist, and upon the amount and 
degree of tapping to which the wire is subjected. 
The longitudinal polarity acquired by a current-bearing wire when 
it is twisted is relatively very high as compared with the probable 
intensity induced at the circumference of the wire. Further, the 
longitudinal intensity so acquired is reversed, more or less com- 
pletely, when the current is reversed. These facts are not easily 
explained in terms of the usual theory of magnetic seolotropy, or 
in terms of any simple hypothesis of rotatable molecules. They 
rather hint at the existence of complex molecular groupings, which 
assume new configurations under the influence of a changing stress 
or a changing magnetic force. 
Certain experiments on the effect of slightly twisting a wire, 
which by superposed magnetisms has been reduced to an apparently 
demagnetised condition, show how easy it is to destroy the apparent 
magnetic balance. There is a strong suggestion that a magnetised 
wire may, under certain circumstances, consist of alternating layers 
of opposite polarities. Any mechanical stress which acts differently 
on these different layers will almost, as a matter of course, power- 
fully affect the average resultant action which is measured on the 
magnetometer. 
From the experiments recorded in the paper, and from the experi- 
ments of other investigators into the complex relations of magnetism 
and twist, the general conclusion may be drawn that the first effect 
of a shearing stress upon the molecular groupings is not only to 
increase the average intensity in the direction of the magnetising 
force, but also to bring into prominence a relatively high intensity 
in directions at right angles thereto. 
