532 
MR. G. GORE ON ELECTROTORSION. 
ivory, G. To the opposite end of the base-board were also fixed by screws (H and I) two 
similar springs (J and K) similarly united by the ivory, L. The screw A was connected 
with I by a stout copper wire beneath the board ; and B was similarly connected with 
H. To the free end of each of the four springs was attached, by means of a small 
screw, a vertical thick wire of platinum which projected beneath the spring for the 
purpose of dipping into one of two small cavities (M and N) containing mercury. The 
screws C and D were also provided with similar wires for dipping into the mercury. 
4 . Is a magnetic metal necessary % 
I tried wires of platinum, silver, copper, lead, tin, cadmium, zinc, magnesium, alumi- 
nium, brass, and German silver, also a zinc rod 2*75 m. long and 11 mm. thick, and 
applied the currents in various ways, but obtained no signs of torsion. A cord of gutta 
percha, strained by a weight, was also subjected to the influence of the coil-current, 
but without effect. 
5. General cause of the torsions. 
The torsions are not due to momentary induction-currents of electricity, because they 
continue as long, and in many cases only as long, as the currents, and because a 
soldered brass tube interposed between the whole length of the coil and the axial wire 
did not prevent or diminish them. 
The most probable cause of the phenomena appears to be the combined influence of 
ordinary induced longitudinal magnetic polarity and of a direction of induced mag- 
netism at right angles to that, producing molecular motion and change of position of 
the particles, the two directions of induced magnetism being caused by the coil and 
axial electric currents respectively. We know by the alterations which occur in the 
length and diameter of a soft iron rod, when it is subjected to the influence of a coil- 
current (discovered by Dr. Joule), and the sounds then produced in it, that a molecular 
movement and change of position of its particles then occur ; and it appears equally 
certain, from the torsions and sounds produced, that whenever an electric current 
traverses the axis of a longitudinally magnetized piece of iron, it also causes a molecular 
movement and change of position of the particles. 
[The phenomena may be explained upon the supposition that a coil-current lengthens 
an iron rod by causing the axes of its molecules to place themselves parallel to the axis 
of the rod ; an axial one places them tangentially ; and the two currents acting together 
place them in a direction intermediate between those two, i. e. in a spiral direction — 
the mass of the iron being in each case lengthened in the direction of the axes of the 
molecules, and shortened in a direction at right angles to that.J 
6. Laic of direction of electrotorsion. 
It might be theoretically anticipated that the torsional movements occur in definite 
directions with relation to the electric currents. This has been found to be the case ; 
and the law of the phenomenon in iron is as follows : — A. With an axial current. A 
