1896 - 97 .] 
Meetings of the Society. 
519 
II. and III. On some relations between Magnetism and Twist in 
Iron and Nickel. Part I. read July 16, 1888; vol. xxxv. 
pp. 377-390. Parts II. and III. read June 1, 1891 ; 
vol. xxxvi. pp. 485-535. 
In these papers many new facts in the subject of magnetic 
strains are recorded. The chief points are : the coordination of 
the Joule and Wiedemann effects; the discovery and explanation 
of a maximum twist in nickel, although there is no maximum 
elongation , in moderate fields ; the observation of the Wiedemann 
effect in cobalt ; the effect of tension on the Wiedemann effect, 
and therefore, by inference, on the Joule effect ; the nature of the 
hysteresis in the Wiedemann effect as either of the magnetising 
forces is taken through a complete cycle ; the curious difference in 
the amount and occasionally in the direction of the twist according 
to the order in which the magnetising forces are applied; the 
magnetic polarity produced by twisting wires conveying currents ; 
the reversal with the current of the polarity acquired by twisting ; 
the residual character of this polarity and its remarkably high 
value, etc. etc. 
IY. The Strains produced in Iron , Steel, and. Nickel Tubes in 
the Magnetic Field. Part I. read January 6, 1896 ; 
vol. xxxviii. pp. 527-555. 
Y. Part II. read June 7, 1897 (not yet published). 
A novel line of research is followed out in these communications, 
which have to do mainly with the effect of magnetism in altering 
the internal volume of tubes of iron and nickel. The effect was 
first noticed in May 1891, in Japan ; and the results were 
communicated to the Royal Society of Edinburgh in July of that 
year (see Proceedings, vol. xviii. pp. 317-9). The subsequent 
experiments, for the carrying out of which tubes of iron, steel, and 
nickel, of suitable form and various bores, were specially prepared, 
were all made in the Physical Laboratory of the University of 
Edinburgh. 
The most important experiments are those that have to do with 
the behaviour of a series of tubes of each metal ' of gradually 
