542 
ME. G. GOEE ON ELECTROTORSION. 
by reversing both. They also prove that the directions of torsion produced by a coil- 
current succeeding an axial one are identical with those produced by an axial current 
following a coil one. 
The general characters of the torsions produced by a coil-current succeeding an axial 
one are very similar to those produced by the reverse order of currents (see Sections 9 
& 10), and indicate that both are produced by the same general cause. 
19. Magnitudes of torsions produced by coil-currents succeeding axial ones. 
The magnitudes of these torsions averaged about two fifths of those produced by axial 
currents succeeding coil ones. With an iron wire 2'6 m. long and 3 mm. thick, and 
a current from 12 cells arranged as 3, coil-currents succeeding axial ones produced 
torsions which varied in magnitude from 1 to 5*25 mm. of movement of the end of 
the index; and with an iron wire 3*77 mm. diameter, supporting a weight of 5^ kilo- 
grammes, the movements varied from *5 to T25 mm. The magnitudes of the torsions 
produced by this method also diminished with increase of thickness of the iron. 
20. Influence of the order of succession of the two currents upon the magnitude 
of the torsions. 
To ascertain this I made four series of experiments with an iron wire T75 mm. 
diameter, supporting no weight ; and employed a current from 4 cells arranged as 2 
for the coil, and one from 8 cells connected as 4 for the axial wire. Twelve single 
currents, i. e. six of each, were transmitted in each series : — 1st Series. With coil- 
currents producing north poles below, alternated with downward axial ones, the 
torsions produced by the coil-currents were all to the right hand, and averaged 1*62 mm. ; 
and those by the axial currents were also in that direction, and averaged T64 mm. 
2nd Series. The same direction of coil-currents, alternated with upward axial ones. 
The torsions produced by each kind of currents were all to the left hand ; those due to 
the coil-currents averaged T60 mm. in magnitude, and those produced by the axial ones 
averaged 2-05 mm. The large inelastic torsions produced on changing from one series 
to another, one of the currents being then reversed, were of course not included in the 
reckoning. 
3rd Series. With coil-currents producing south poles below, alternated with down- 
ward axial ones. The coil-currents produced torsions to the right hand*, and the 
axial ones produced torsions to the left. The former averaged ’91 mm. in magnitude, 
and the latter 3-82 mm. 
4 th Series. With coil-currents in the same direction, alternated with upward 
axial ones, the torsions yielded by the coil-currents were to the left hand*, and 
averaged *8 mm. in magnitude, whilst those due to the axial ones were to the right 
hand, and their average range was 5-21 mm. The average magnitude of all the coil- 
current torsions in the 4 series was 1*23 mm., and of axial-current ones 3*18 mm. : 
* The apparently abnormal direction of these torsions will be treated of subsequently (see Section 21). 
