536 
ME. G. GOEE ON ELECTEOTOESION. 
others in the same direction, and which produced the small elastic torsions only, were 
more metallic, and those which succeeded currents in an opposite direction, and pro- 
duced the large inelastic torsions, were more dull. Those produced by repetition 
currents in the same direction did not appear to diminish in loudness in proportion to 
the diminution of magnitude of the torsions. Axial currents succeeding coil ones were 
also tried ; each yielded a feeble sound at its commencement and none at its termi- 
nation. In every instance in which torsion occurred there was sound emitted, and in 
every case where no sound was produced no torsion took place ; probably therefore the 
two phenomena are mutually related, and the torsion is dependent upon the cause 
which produces the sound. 
[We know that by the passage of coil-currents alone around an iron wire, or axial 
currents alone through it, sounds without torsion occur ; and the experiments of De 
la Rive (Phil. Trans. 1847, p. 40; Phil. Mag. vol. xxxi. 1847, p. 328, and vol. xxxv. 
1849, p. 428) have shown that such currents produce sounds in various non-magnetic 
substances, and those substances do not exhibit electrotorsion (see Section 4) ; and as 
the object of this research was to examine the torsion and not the sounds, I have not 
investigated the latter phenomena except in such cases as they appear to be connected 
with the former.] 
It is manifest, from a consideration of the torsions and sounds, that an electric current 
passed through iron in a more or less magnetized state produces a molecular move- 
ment and a change of position of its particles, and that the new position continues as 
long as the current. Also that, on the cessation of the current, the particles make very 
little movement, and return only a small extent towards their original positions, because 
little or no sound occurs, and only a small amount of detorsion then takes place. Also 
that an electric current in the opposite direction produces a similar set of changes, except 
that the changes are in the reverse direction. 
The small detorsions which occur on the cessation of every single axial current 
succeeding a coil one appear to be due to the reaction of the ordinary mechanical 
elasticity of the metal ; but that is a point I have not examined. 
13. Distribution of coil-current influence in the helix. 
In order to ascertain whether the torsional influence of the. helix was less at the 
middle of the coil than at its extremities, I tried its effect upon an iron wire 61 centims. 
( = 24 inches) long and T37 mm. diameter, in the two positions, the remainder of the 
axial conductor being formed of thick copper wire upon which the two currents have 
little or no torsional effect. The current from 12 Grove’s cells was applied in the 
most effective way, and in the same manner in each case. A series of four torsions was 
produced in each position, those produced by the wire at the middle of the coil being 
obtained after the others; the former averaged 6’44 mm. and the latter 6T1 mm. If, 
therefore, a small allowance be made for the gradual weakening of the current, the 
degrees of torsional influence at the middle part of the coil and at its ends are about 
