On Magnetic Lagging and Priming in Twisted Iron 



and Nickel Wires. 



By 

 Cargill G. Knott, D.Sc. (Edin.\ F.R.S.E., 



Professor of Physics, Imperial University, Tokyo. 



In 1886, Professor Wiedemann published some very interesting 

 experiments on the effects of twist on iron and nickel wires, variously 

 magnetised.* These, however, were in themselves too few to guide 

 us to any very clear knowledge of the relations of magnetism and 

 twist. A consideration of them at once suggested innumerable lines 

 of enquiry, and opened up vast gaps in our knowledge which prolonged 

 experiments alone could fill. Shortly put, here is an iron or nickel 

 wire of certain dimensions, magnetised in a certain manner either 

 permanently or temporarily, and subjected to a particular straining 

 involving twist. The problem is to find how all these different pos- 

 sible variable quantities or qualities depend on one another. 



With a view to work out some small part of this huge problem, 

 I sketched out a line of research, which was partly carried through 

 in 1887 by Mr. K. Imagawa, a graduating student of Physics in the 

 Imperial University of Japan. During the first six months of that 

 year, many distinct series of experiments were made. 



The complete discussion of these and other experiments carried 



* Se3 Wiedemann's Anualen, Vol. XXVII., p. 377 ; translated in the Philosophical Maga- 

 ine (188G), 



